Size, shape, orientation, and distribution of tree islands in a remnant of northern Everglades wetland were examined from 1950 and 1991 aerial photography. The objectives were to quantify the patterns of tree islands in Loxahatchee National Wildlife Refuge, to determine if the patterns of tree islands had changed between the two dates, and to relate the tree island patterns to modeled pre- and post-drainage hydrologic patterns. There was considerable variation in the patterns of tree islands spatially and temporally. Changes in the size and shape of tree islands from 1950 to 1991 are consistent with changes in the modeled pre- and post-drainage hydrologic patterns. Photo plots along the edges of the refuge, where hydroperiods are longer and depths deeper than they were historically, show a decrease in tree island size and in overall area of tree islands in the plots. Photo plots in the interior, where hydroperiods are shorter than they were pre-drainage, show an increase in tree island area. Overall, there is a tendency for more tree islands to be irregularly shaped in the 1991 photo plots than in the 1950 plots, a reflection of the loss of water flow, reduction of pulse magnitude, and the ponding of water along the perimeter dikes. This study illustrates the importance of considering long-term changes in hydroperiod, depths, and water flows in the restoration of this area.

Factors affecting growth of softstem bulrush (Scirpus validus), an obligate wetland plant frequently used in subsurface-flow constructed wetlands in North America, were studied in a controlled environmental chamber. Effects of media depth (30- and 46-cm), hydraulic retention time (HRT) (2- and 6-day), and water-level drawdown (drawdown vs. no drawdown) on plant growth in 24 microcosms were investigated. Weekly root and stem growth was measured and stem health assessed to determine effects of treatments on plant vigor. Water-level drawdown was detrimental to plant growth, increasing the percentage of dead stems. Stem production was higher in microcosms with a 46-cm media depth than those with a 30-cm depth and also higher in microcosms that were permanently flooded than in those with fluctuating water levels. Root production was greater in microcosms with a 30-cm media depth than in those with a 46-cm depth, and root production was also greater in microcosms that were constantly flooded than in those drawn down. Scirpus validus is a robust plant that grows well in gravel media microcosms; however, problems are experienced when rhizomes and roots dry out during water drainage.

Sediment organic matter content, bulk density, and hydraulic conductivity were examined in 56 sediment cores collected from a small lotic wetland in the Talladega Wetland Ecosystem (Hale County, Alabama, USA). All sediment characteristics varied spatially across the wetland. A distinctive demarcation in sediment characteristics occurred between the upper (0 to 30-cm) and lower (30 to 80-cm) depths. Sediments in the upper 30-cm contained a higher percentage of clay than deeper sediments and had high hydraulic conductivities (0.5 to 1100 cm d⁻¹). Lower sediment depths contained greater percentages of silt and sand, but greater sediment compaction and lower organic matter concentrations resulted in low hydraulic conductivities (1 × 10⁻³ to 55 cm d⁻¹). Higher organic matter and lower bulk density occurred in the sediments of vegetated areas of the wetland compared to the areas near the inflow and outflow streams. Organic matter was higher and more variable (2 to 38% sediment dry weight) within the upper 30 cm of sediments and decreased significantly with depth (r² = 0.51). In the lower sediments (30 to 80-cm depth), organic matter was lower and less variable (2 to 10% sediment dry weight). Sediment bulk density increased with increased sediment depth (r² = 0.77) and was lower in vegetated areas (0.2 to 1.0 g cm⁻³) compared to the inflow and outflow stream sediments (0.6 to 1.4 g cm⁻³).

Although the importance of hydrology to wetland ecosystem productivity is recognized, there are few detailed analyses of shallow subsurface water flow (<1 m depth) through wetland ecosystems. Shallow subsurface water flow paths and average linear velocity were quantified with nested lysimeters in a riverine wetland located in Hale County, AL. Water-table elevation was spatially and temporally variable and was directly correlated to precipitation at the wetland. In the beginning portion of the study (May to November 1996), average monthly precipitation was 73 mm and water-table elevation decreased across much of the wetland. From December 1996 through July 1997, average monthly precipitation increased to 110 mm with a concomitant increase in water-table elevation throughout the wetland. During periods of low average monthly precipitation, wetland subsurface water was recharged from the hyporheic zone of the main inflow stream (northern side of the wetland). With increased precipitation, subsurface water recharge shifted from the stream hyporheos to recharge from an upgradient area (entire northern portion of the wetland) dominated by alder, Alnus serrulata. Horizontal and vertical average linear velocity was greatest in the upper 20 cm of the wetland compared to lower sediment depths. Vertical average linear velocity was similar among most sample intervals and was not correlated to antecedent precipitation. In laboratory mesocosm experiments, evapotranspiration by the emergent macrophyte Juncus effusus increased the rate of subsurface water flow in mesocosms with sand sediments, while there was no macrophyte effect in mesocosms with predominantly clay sediments.

Hydrology and water quality distributions in a Louisiana forested waste-water treatment wetland were studied under four different hydraulic loading rates (HLR). Pond discharge, surface-water elevations, and fluorescent dye travel times were recorded to assess surface-water hydrology, and water samples were collected for nitrate, ammonium, phosphate, and suspended solids analyses. Wetted surface area increased with pond discharge rate, and 58 to 66 percent of surface-water flow was concentrated in shallow channels covering only 10 to 12 percent of the total study area. Water residence times were much longer (0.9 to 1.1 days) than minimum dye travel times (2 to 3 hours) through the 4-hectare study area. Relative to study area influent concentrations, study area outflow concentrations of nitrate and total and organic suspended solids were lower, ammonium was higher, and phosphate was generally unchanged. However, there was an increase in concentrations of nitrate, ammonium, and phosphate within 50 m of the study area inflow location. Ammonium and phosphate did decrease from these peak concentrations. Net nitrate production was observed within 50 m of the pond outfall and was probably due to nitrification. Net nitrate removal was observed beyond this distance and ranged up to 0.10 g · m⁻² · d⁻¹ probably due primarily to denitrification. In general, nitrate removal rates increased linearly with changes in nitrate loading rates. Results show that nutrient distributions are linked to hydrology. Higher pond discharge rates created more treatment surface area, and higher constituent loading rates produced higher removal rates. Therefore, discharge rates could be manipulated, and physical control structures could be installed to increase wetted surface area and increase removal efficiency within the wetland. Higher loading rates could then be processed without requiring significant increases in treatment area.

Sulfur transformations in freshwater peat were studied using contrasting stable isotope signatures of atmospheric input (high δ³⁴S) and Sphagnum peat substrate (low δ³⁴S). Wet subsurface peat samples from the Lehstenbach watershed, Fichtelgebirge, Germany were incubated anaerobically at 5 and 15°C. Pore-water sulfate was augmented with natural precipitation at the onset of the experiments. Sulfate concentrations and δ³⁴S ratios of residual pore water were measured in 1-day intervals (9 days) and 1-week intervals (7 weeks) at 15°C, and in 1-week intervals (7 weeks) at 5°C. Initially, SO₄²⁻ concentrations decreased (by 50 to 85%) and δ³⁴S ratios increased (by as much as 16‰) at both temperatures due to bacterially-mediated dissimilatory sulfate reduction. At the higher temperature (15°C), the S isotope effect (Δ δ³⁴S) was higher than at the lower temperature (5°C). On day 4 (at 15°C) and day 29 (at 5°C), the δ³⁴S ratio of pore-water sulfate started to decrease by as much as 20‰. The changing S isotope composition provided evidence for a dynamic turnover of the pore-water sulfate pool in anaerobic peat. The observed δ³⁴S pattern could not be explained solely by isotope selectivity of the sulfate-reducing bacteria. Sulfur isotope data indicated a replenishment of the sulfate pool by hydrolysis of ester-sulfate.

The placement of wetland restoration projects in a landscape to optimize the functional performance of wetlands on a regional scale is often overlooked. To address this problem, the U.S. Environmental Protection Agency's Landscape Function Project developed the synoptic approach to assign restoration priority to landscape subunits according to selected functional criteria. The approach provides a flexible, ecologically-based framework for allocating limited restoration-resources and preserving valued wetland functions on a landscape scale. We conducted a synoptic assessment of the Prairie Pothole Region of the north-central U.S. to demonstrate application of the method for our assessment criterion—the marginal decrease in total downstream flood volume per restoration dollar. A criterion is often not directly measurable but can be represented by an index composed of measurements on related variables. In a synoptic assessment, these measured variables, referred to as indicators, are limited to variables for which data are existing, accessible, and uniformly available for the entire region. We developed a conceptual model to guide the development of an index of the assessment criterion. We then ranked landscape subunits based on index values and mapped the ranks to show relative priority for restoration among landscape subunits. We conducted a series of analyses to justify selection of indicators and some of our assumptions. The approach offers multiple options for processing and displaying information for use by wetland managers.

We studied the relationship between benthic invertebrates and aquatic birds at a newly constructed wetland using an avian exclosure experiment combined with counts of aquatic bird use. We measured the standing stock biomass of benthic dipterans both inside and outside exclosures. Chironomidae was the most abundant dipteran family present. Maximum chironomid standing stock biomass per pond ranged from 3.62 to 27.82 g/m² and was comparable to that found in a number of natural systems. We monitored the abundance of ten aquatic birds species. Abundances of three aquatic bird species [American avocet (Recurvirostra americana), Wilson's phalarope (Phalaropus tricolor), and cinnamon teal (Anas cyanoptera)] were significantly correlated with chironomid and total dipteran densities. Our experiment, however, found no significant effect of predation on invertebrate densities.

Field and laboratory studies were conducted to evaluate the use of bacterial growth on aquatic insects as a metric for determining the existence of nutrient impacts in wetlands. Results from field investigations indicated that elevated concentrations of nitrate and phosphate were associated with growth of filamentous bacteria on insect body surfaces and that there were significantly fewer mayflies (Ephemeroptera) in the nutrient-enriched wetland. Laboratory investigations confirmed a strong linkage between bacterial growth and reduced survival of mayflies. Survival was examined for individuals with bacterial infestation ranging from 0% to 60% body coverage. A threshold for catastrophic mortality was present at about the 25% level of coverage; there were very few survivors above that level. Based on these findings, the diagnostic endpoint for the bioindicator is 25% body coverage by bacterial growth, a level that signifies major differences in insect populations in the field and is also easy to detect visually. This study provides evidence that the insect-bacteria bioindicator is a reliable tool for assessing nutrient impacts on wetland macroinvertebrate communities. The bioindicator could be useful in the development of a Wetland Bioassessment Protocol.

Forest removal represents one of the large-scale ecosystem disturbances that concern water quality degradation, species composition change, and wildlife habitat alteration along the Florida coast. We conducted a five-year study with the objective to address effects of two forest management scenarios on the water regimes of cypress-pine flatwoods ecosystems in the lower coastal plain. Three experimental blocks (16–21 ha) were used in this study, with one representing control (C), one wetlands-harvest-only (W), and one wetlands uplands harvest (ALL). Within the center of each block, a representative cypress wetland and its surrounding pine upland were extensively instrumented to quantify the changes of each hydrologic variable induced by tree removal. Water levels in cypress wetlands in both treatment areas were significantly elevated about 32–41 cm on average, and outflow doubled in the five-month dry period immediately following the tree harvesting. The ground-water table in the upland was also raised by about 29 cm on average due to ALL, but it was not affected significantly during the entire post-treatment period by W. During wet periods, the treatment effects for both wetlands and uplands were not significant. Causes for spatial and temporal variability of hydrologic responses to forest harvesting are speculated to be 1) total evapotranspiration does not change significantly in flatwoods after tree removal during wet seasons; 2) specific yield of the flatwoods soils is variable in time and space; and 3) lateral water movement from uplands to wetlands. From this study, we conclude that harvesting both uplands and wetlands causes greater response than harvesting wetlands only. The impacts lasted for more than two years but were most pronounced only in the dry periods. Temporal and spatial variations of each hydrologic component should be considered in evaluating the hydrologic impact of forest management on the flatwoods landscape.

In five tributary streams (four inflowing and one outflowing) of 1600-ha Trout Lake in northern Wisconsin, USA, we examined factors that can affect the magnitude of stream flow and transport of dissolved organic and inorganic carbon (DOC and DIC) through the streams to the lake. One catchment, the Allequash Creek basin, was investigated in more detail to describe the dynamics of carbon flow and to identify potential carbon sources. Stream flows and carbon loads showed little or no relation to surface-water catchment area. They were more closely related to ground-water watershed area because ground-water discharge, from both local and regional sources, is a major contributor to the hydrologic budgets of these catchments. An important factor in determining carbon influx to the stream is the area of peatland in the catchment. Peatland porewaters contain DOC concentrations up to 40 mg l⁻¹ and are a significant potential carbon source. Ground-water discharge and lateral flow through peat are the suspected mechanisms for transport of that carbon to the streams. Carbon and nitrogen isotopes suggested that the sources of DOC in Allequash Creek above Allequash Lake were wetland vegetation and peat and that the sources below Allequash Lake were filamentous algae and wild rice. Catchments with high proportions of peatland, including the Allequash Creek catchment, tended to have elevated DOC loads in outflowing stream water. Respiration and carbon mineralization in lakes within the system tend to produce low DOC and low DOC/DIC in lake outflows, especially at Trout Lake. In Allequash Lake, however, the shallow peat island and vegetation-filled west end were sources of DOC. Despite the vast carbon reservoir in the peatlands, carbon yields were very low in these catchments. Maximum yields were on the order of 2.5 g m⁻² y⁻¹ DOC and 5.5 g m⁻² y⁻¹ DIC. The small yields were attributable to low stream flows due to lack of significant overland runoff and very limited stream channel coverage of the total catchment area.

We described the vegetation of two alluvial swamp forest stands along Durham Creek in Beaufort County, North Carolina, USA in relation to elevation, hydrologic, and edaphic gradients. Over 3,000 surveyed elevations of individual plant microsites were used in conjunction with 26 years of stream gage data to examine individual species responses to annual and growing season flooding frequencies. Direct gradient analyses combined with plot ordinations derived from detrended correspondence analysis and canonical correspondence analysis suggested that differences in vegetation between the stands were primarily the result of variations in elevation, growing season flooding frequency, percent base saturation, exchangeable acidity, and soil physical properties. Although the stands were less than 4.5 km apart and without significant intermediate tributaries, growing season flooding frequency and duration were magnified in the lowest elevations of the downstream stand. An elevation difference of as little as 10 cm resulted in a 20% difference in the frequency of surface flooding during the growing season. Species distributions were significantly correlated with depth to mottling (r² = 0.75), flooding frequency (r² = −0.57), elevation (r² = 0.70), and several soil chemical properties. The two stands had very similar annual surface flooding regimes, but subtle differences in growing season flooding frequency, soil characteristics, and disturbance history have apparently resulted in dissimilar plant community composition and structure. These results suggest that the lack of quantitative data on vegetation-environment interactions occurring at the microtopographic scale (10⁻¹ m) in alluvial swamp forests makes precise prediction, planning, or design of created or restored wetland composition and function a formidable challenge.

Wetland scientists and managers recognize the need to characterize hydrology for understanding wetland ecosystems. Hydrologic data, however, are not routinely collected in wetlands, in part because of a lack of knowledge about how to effectively measure hydrologic attributes and how frequently to measure water levels. To determine how measurement interval affects interpretation of water-level data, we analyzed data from seven wetlands in Oregon and Pennsylvania. We created subsets of daily data for each wetland, with measurement intervals of 2 to 28 days, then compared those subsets to the daily data for annual water-level summary statistics, monthly mean water levels, and occurrence/duration of threshold conditions (e.g., water in the root zone). Our primary goal was to determine if sampling at low frequencies can provide representative water-level data and accurate perceptions of the occurrence of water levels above thresholds. For annual water-level distributions, small data sets from 28-day measurement intervals provided summary data (e.g., median, quartiles, range) comparable to the 1-day reference data. For measurement intervals of seven days or less, average errors in estimates of stage (minimum, 25th, 50th, and 75th percentiles) were ≤ 0.03 m; for a 28-day interval, average errors were <0.05 m. Errors in estimates of maximum stage were considerably larger (0.11 m and 0.21 m for 7- and 28-day intervals, respectively) but can be circumvented using crest gauges. Errors in estimates of monthly mean stage varied greatly with measurement frequency (1–4% error for 7-day intervals, 5–15% error using one measurement per month), among wetlands and from month to month. Water-level durations above threshold values were problematic; for measurement intervals of 2 days and longer, 14-day exceedances of water in the root zone were frequently missed or spurious exceedance periods were identified. Overall, results show that sampling at monthly intervals, supplemented with crest gauges, provides a representative description of annual water-level distributions for use in classifying and comparing wetlands. More frequent sampling is required to characterize water levels for shorter (e.g., monthly) time periods and to reliably identify exceedance periods for water above threshold levels. More generally, the results remind us that the frequency and duration of sampling in hydrologic studies must be designed to ensure that data will support planned analyses.

This experiment examined how elevation and control of early successional vegetation would affect the growth and survival of tree species used in restoration. Vegetation was controlled by either mowing or spraying with Accord [glyphosate, –(phosphononomethyl)glycine, in the form of its isopropylamine salt] herbicide. These control methods were applied to either the entire plot or a narrow 1-m strip where seedlings were to be planted. A fifth treatment (control) had seedlings planted into the existing vegetation. Species planted were baldcypress (Taxodium distichum), water tupelo (Nyssa aquatica), willow oak (Quercus phellos), Nuttall oak (Q. nuttallii), overcup oak (Q. lyrata), and cherrybark oak (Q. falcata var. pagodaefolia). Seedlings were randomly planted in late April 1993 with six rows in each plot and six trees per row on a 2 × 2 m spacing with five replicate plots per treatment. Survival was not enhanced by any competition control treatment, but survival among species differed. All six species had overall survival > 90% in autumn 1993. Species survival was affected by several summer floods during 1994. Baldcypress and overcup oak survival was greater than 89%, while water tupelo, Nuttall oak, and willow oak were all approximately 70%, and cherrybark oak was only 29%. By the end of 1995, survival of all species decreased further, but the species groupings remained the same. Survival and height growth of baldcypress and water tupelo were greatest at lower planting elevations. At higher elevations, survival of cherrybark oak and willow oak were greatest, while overcup oak and Nuttall oak were unaffected by elevation. Thus, controlling the herbaceous vegetation did not affect survival or growth as much as relative planting elevation due to site flooding and the flood tolerance of the species. All of the species in this experiment except cherrybark oak were successfully established.

Dead, downed wood is an important component of upland forest and aquatic ecosystems, but its role in wetland ecosystems, including mangroves, is poorly understood. We measured downed wood in ten sites on the western Pacific islands of Kosrae, Pohnpei, and Yap, all located within the Federated States of Micronesia. Our goals were to examine patterns of variability in the quantity of downed wood in these mangrove ecosystems, provide a general characterization of downed wood in a region with no previously published accounts, and investigate the relationship between harvesting practices and the amount of downed wood. The overall mean volume of downed wood at our study sites was estimated to be 60.8 m³ ha⁻¹ (20.9 t ha⁻¹), which is greater than most published data for forested wetlands. There were significant differences among islands, with the sites on Kosrae (104.2 m³ ha⁻¹) having a much greater mean volume of downed wood than those on Pohnpei (43.1 m³ ha⁻¹) or Yap (35.1 m³ ha⁻¹). Part of the difference among islands may be attributable to differences in stand age and structure, but the most important factor seems to be the greater amount of wood harvesting on Kosrae, coupled with a low efficiency of use of cut trees. Of a total of 45 cut trees examined on Kosrae, no wood had been removed from 18 (40%); these are believed to be trees cut down because other, more valuable, trees were caught on them as they were felled. Of the other 27 trees, only 24 to 42% of the stem volume (to a 10 cm top) was removed from the forest, the amount varying by species. The impacts of current harvesting practices are unknown but may include important effects on tree regeneration and the abundance and species composition of crab populations.

The U.S. Fish and Wildlife Service and Canadian Wildlife Service incorporate information from annual aerial and ground counts of waterfowl into harvest management strategies. Timing of population surveys is thought to be optimal for early nesting species but may not reliably reflect the status of species with later migration chronology. The purpose of this study was to evaluate effects of survey timing on diving duck and duck brood abundance indices in eastern South Dakota. Findings indicate that timing of aerial breeding surveys occurred too early in eastern South Dakota to accurately reflect diving duck population status because birds had not yet settled into breeding habitats and aerial production surveys did not coincide with peak duck brood abundance. Diving duck abundance from aerial surveys conducted during 10–17 May were higher than indices from ground surveys conducted 2 weeks later because lesser scaup (Aythya affinis), ring-necked duck (Aythya collaris), and bufflehead (Bucephala albeola) were still migrating through eastern South Dakota. Ground-survey estimates of redhead (Aythya americana) and canvasback (Aythya valisineria) abundance exceeded the upper limit of 95% confidence intervals for aerial survey estimates. Results from our second year of study showed an 11-fold decrease in lesser scaup abundance and an 8-fold decrease in ring-necked duck abundance in the two weeks following aerial breeding surveys. Brood abundance of dabbling and diving ducks peaked 1–1.5 months after aerial production surveys conducted in early July. Late-nesting indices calculated from aerial surveys were unrelated (P = 0.21) to number of late-hatching broods, whereas number of broods hatching after aerial surveys was correlated with late-nesting indices from ground surveys (r² = 0.74, P < 0.01) and with number of July ponds (r² = 0.77, P < 0.01). We encourage scientists to initiate a more thorough evaluation of survey biases to ensure that trends accurately reflect status of duck populations and to explore the possibility of using a separate late May/early June aerial survey after diving ducks have settled into habitat as a way of assessing breeding population trends for these species.

We used time-activity budget techniques to measure foraging behavior of green-winged teal (Anas crecca carolinensis) and mallards (A. platyrhynchos). Observations were made on tidal mudflats in the Atchafalaya River Delta, Louisiana, USA, in the winter of 1994–1995. Green-winged teal spent more diurnal time than mallards foraging (68% vs. 35%). Time spent in different foraging postures also differed between species. Green-winged teal foraged by dabbling 70% of the time and by head-dipping only 28% of the time. Mallards foraged by dabbling 47% of the time and by head-dipping 47% of the time. Foraging by tipping-up was rare in both species. Mean water depths used by both species when foraging were <5 cm. Most foraging took place near the mud-water interface during ebb and flow tides.

Nutrient properties of wetlands are primary evaluated by soil chemical analysis. Therefore, appropriately collecting and storing waterlogged soil samples is crucial to accurately representing in situ soil-nutrient conditions. A west Texas playa wetland and surrounding outerbasin soils were sampled to compare the effects of three soil storage techniques on various chemical constituents. Techniques evaluated were the following: (1) drying at room temperature, (2) freezing, and (3) purging with nitrogen gas. Drying and freezing are typical methods used in storing terrestrial soils. We hypothesized that the purging technique would facilitate an anaerobic environment and inhibit aerobic chemical transformations. Soils were analyzed for total Kjeldahl nitrogen (TKN), NO₃ NO₂-N, NH₄-N, extractable P, Cu, Fe, Mn, Zn, and pH. Values for NO₃ NO₂-N and Cu were significantly greater in dried samples than both frozen and purged samples, and generally were significantly lower in pH. Based on this study, we recommend that wetland soils not be dried before analysis.

The Everglades crayfish (Procambarus alleni Faxon) is the only species reported from Everglades National Park (ENP) and Big Cypress National Preserve (BICY). However, we identified a second species, Procambarus fallax (Hagen), from those locations. Reexamination of archived samples showed that P. fallax had been collected as early as 1985 but had been misidentified or overlooked; therefore, we provide methods for distinguishing live and preserved specimens of these morphologically similar species. Species relative abundance varied predictably with hydroperiod (length of inundation) both in recent collections and in archived samples. Procambarus fallax relative abundance was highest in sites characterized by long hydroperiod and prolonged inundation, whereas P. alleni was the lone species in short hydroperiod marshes.

Studies have documented the flora, fauna, and soils of ground-water fed wetlands, but very little is known about their plant-mycorrhizal associations. This study was designed to determine the presence of arbuscular mycorrhizal (AM) fungi in several wetland plant species associated with fens in west central Ohio, USA. Roots of wetland plant species collected at four sites had mycorrhizal fungal colonization levels ranging from 0 to 61.5%. Mycorrhizal associations occurred in plants of all wetland categories (OBL, FACW, FAC). We propose that these peatlands have lower nutrient availability than some other wetlands and thus may be more dependent on these root fungi for nutrient uptake. Mycorrhizal fungi may be an important consideration in the functional restoration of ground-water driven wetland systems.

We developed a surface-associated activity trap (SAT) for sampling aquatic invertebrates in wetlands. We compared performance of this trap with that of a conventional activity trap (AT) based on non-detection rates and relative abundance estimates for 13 taxa of common wetland invertebrates and for taxon richness using data from experiments in constructed wetlands. Taxon-specific non-detection rates for ATs generally exceeded those of SATs, and largest improvements using SATs were for Chironomidae and Gastropoda. SATs were efficient at capturing cladocera, Chironomidae, Gastropoda, total Crustacea, and multiple taxa (taxon richness) but were only slightly better than ATs at capturing Dytiscidae. Temporal differences in capture rates were observed only for cladocera, Chironomidae, Dytiscidae, and total Crustacea, with capture efficiencies of SATs usually decreasing from mid-June through mid-July for these taxa. We believe that SATs may be useful for characterizing wetland invertebrate communities and for developing improved measures of prey available to foraging waterfowl and other aquatic birds.