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The Prairie Pothole Region (PPR) of North America has experienced extreme changes in wetland habitat due to proliferation of invasive plants. Typha × glauca is a highly competitive hybrid between native T. latifolia and non-native T. angustifolia, and it is likely the predominant taxon in PPR wetlands. Genetics-based studies are limited, and distributions are poorly known for the first-generation (F1) hybrid and advanced-generation hybrids from F1 mating. Information pertaining to the distribution of T. × glauca could benefit efforts to understand the mechanisms of its spread and to develop management strategies to limit hybrid expansion and preserve progenitors. We used microsatellite markers of field-collected tissue samples from 131 wetlands spread over approximately 350,000 km2 in the PPR to assess the distribution of hybrid T. × glauca relative to its parental species and to examine the prevalence of F1 hybrids and advanced-generation hybrids. Typha × glauca was found in over 80% of wetlands throughout the PPR, compared to 26 and 18% of wetlands with T. latifolia and T. angustifolia, respectively. Advanced-generation hybrids were more common than F1 hybrids, suggesting that hybridization is not a recent phenomenon. Hybrids were significantly taller than T. latifolia, indicating heterosis. Only 7% of sampled individual genets were pure T. latifolia. These results suggest that T. × glauca is pervasive throughout the PPR and may spread independently of both parents. In addition, limited prevalence of native T. latifolia indicates the need for active management to preserve the species.

A time-series (1990–2013) of classified vegetation cover maps was produced for Netley-Libau Marsh, a 26,000 ha coastal wetland on Lake Winnipeg, to assess its current status and verify earlier trends of emergent vegetation loss. Open water area in the marsh was measured from late-summer Landsat images for 20 years; three classes of vegetation types (emergents, wet meadows, upland) could also be identified for 12 images covering the same period. Temporal changes in area and distribution of marsh vegetation were related to adjoining Lake Winnipeg water-level and Red River discharge, as well as marsh connectivity and bathymetry. From 1990 to 2002, an increase in open-water areas and decrease in emergent vegetation coincided with rising levels and flows. The year 2003 marked major wetland regeneration and a decrease of open-water area under extremely low water-levels and flows. From 2005 to 2013, open-water area remained consistent, under high but variable levels and flows. A strong negative correlation was found between area of emergent vegetation and mean Red River discharge in the previous June-July. Superimposition of the limit of new emergent vegetation observed in 2003 with depth contours surveyed in 2010 revealed the dynamic nature of marsh bathymetry. Periods of extremely low water as short as one year (2003) induced a marked expansion in emergent vegetation cover that persisted over the next ten years despite higher water-levels. Rather than being gradual, changes in the spatial extent of Netley-Libau Marsh vegetation appeared to proceed by fits and starts, wherein periods of relative stasis were disrupted by major changes in abundance.

We examined the interactions of the common carp (Cyprinus carpio L.) and nutrient additions on water quality, sedimentation rates, and submerged macrophyte biomass in mesocosms in Delta Marsh, Manitoba, Canada. We wanted to determine if carp and nutrients interacted synergistically to increase phytoplankton biomass. A two-by-three duplicated, factorial design had the following treatments: (1) control mesocosms with no carp or nutrient additions; (2) low carp density and no nutrient additions; (3) high carp density and no nutrient additions; (4) no carp and nutrient additions; (5) low carp density and nutrient additions; and (6) high carp density and nutrient additions. The presence of carp increased ammonia concentrations, turbidity, and phytoplankton biomass as expected but did not increase total reactive phosphorus concentrations. The presence of carp did not appear to interact synergistically with nutrient additions to increase phytoplankton as has been suggested by others. In mesocosms with high carp density and receiving nutrient enrichment, phytoplankton appeared to be suppressed relative to mesocosms receiving nutrient enrichment only, and nutrient enrichment and low carp density. Overall, the presence of carp appears to mimic the effects of eutrophication. Our results demonstrate that carp can cause a shift from a clear, macrophyte-dominated state to a turbid phytoplankton-dominated state at a biomass of less than 600 kg ha−1.

This study explores the possible applications of a spring complex, East German Creek (EGC), Manitoba, Canada, as a terrestrial analogue for similar environments on Mars. Potential ancient spring deposits have been identified by Allen and Oehler (Allen, C.C., Oehler, D.Z. [2008]. Astrobiology 8, 1093–1112) in Vernal Crater, Arabia Terra, as well as in the intercrater plains of Terra Sirenum by Wray et al. (Wray et al. [2011]. J. Geophys. Res., 116, 1–41). EGC can provide guidance in the search for fossil spring deposits on Mars by using comparative mineralogy to contrast mineral identification from field studies to that available from remote sensing instruments such as the CRISM instrument aboard the Mars Reconnaissance Orbiter. The formation processes of EGC are also useful for finding spring-like environments on Mars. A variety of techniques were employed (X-ray diffractometry, reflectance spectra, water chemistry analysis) to analyze mineralogical changes in spring water precipitates with distance from the main springs at EGC, which were compared with concentrations of dissolved species in outflow water. Biosignatures in outflow stream sediments as well as the effect of surficial Fe oxyhydroxide coatings on the detection of underlying carbonate absorption features have also been spectrally characterized. Halite is the main mineral precipitated at EGC, followed by gypsum, and calcite. The presence of gypsum is readily detected in surficial precipitate spectra while halite does not have a diagnostic spectral signature in the 0.35–2.5 μm region. An absorption feature indicative of chlorophyll a is present in stream sediment spectra from most sampling stations and on outwash plain sediments. Carbonates appear to be spectrally detectable through a coating of ferric minerals, such as goethite by a characteristic absorption band near 2.3 μm. We attempted to detect significant spectral changes over an area of potential spring features in Vernal Crater on Mars using CRISM data over the 1.0–3.92 μm interval, but results were inconclusive. Analysis of the surficial geology, geomorphology, biology, and water chemistry of EGC provides a number of insights into the possible nature of low-temperature spring deposits on Mars, while highlighting the limitations of spectroscopy without the cooperation of X-ray diffractometry.

QuickBird satellite imagery and object-based classification were used to map emergent macrophyte response in wetlands that were partially drawn down during a three-year period (2007–2010) in the Saskatchewan River Delta, Manitoba, Canada. Generalized logistic models were used to classify vegetation genera in three drawdown and three high-water (control) wetlands. User accuracy of models averaged 74 %, and was lower in partial drawdown wetlands (72 %) than in high-water wetlands (77 %). In partial drawdown wetlands, emergent macrophytes (especially Typha spp. and Carex spp.) senesced significantly after the first year of lowered water levels but senescent areas decreased over following years. Plants were not completely dead in dewatered areas and emergent stands recovered by the third year after drawdown. Open water area in the partial drawdown wetlands gradually decreased due to clonal expansion of Sparganium spp. Vegetation areas in high-water wetlands remained unchanged throughout the study period. Although partial water-level drawdowns temporarily influenced the growth of emergent macrophytes they did not expose the seed bank and did not result in substantial, prolonged changes in spatial arrangement of vegetation areas. The combination of high-resolution satellite imagery, object-based classification and logistic modeling was useful for documenting vegetation response to management in these remote, boreal wetland systems.

We compiled an GIS-based inventory of coastal wetlands associated with the Manitoba Great Lakes—Lakes Winnipeg, Manitoba, and Winnipegosis—using a hydrogeomorphic classification system, orthophotography, satellite imagery, and digital habitat maps. The lakes have six times more wetlands per km of shoreline than the Laurentian Great Lakes: Lake Winnipeg has 1404 km 2 (0.8 km 2 /km), Lake Manitoba has 564 km 2 (0.6 km 2 /km), and Lake Winnipegosis has 742 km 2 (0.8 km 2 /km). Riverine wetlands are the most common class on Lakes Winnipeg and Winnipegosis whereas barrier-protected wetlands are the most common class on Lake Manitoba. The totals for Lakes Winnipeg and Winnipegosis are greater by 548% and 273%, respectively, if Treed Muskeg habitat in the northern regions of the watersheds is included in the inventory, whereas the total for more southerly Lake Manitoba is greater by only 18%. Netley-Libau Marsh (222 km 2 ) on Lake Winnipeg and Delta Marsh (139 km 2 ) on Lake Manitoba are among the largest coastal wetlands on the North American continent. These baseline data can be used to identify ecologically important wetlands warranting further study or remediation.

The Common Carp (Cyprinus carpio )i s an exotic benthivorous fish that can have negative impacts in aquatic ecosystems. This study examines the direct and indirect ecological impacts of Common Carp on water column nutrient concentrations, suspended solids, sedimentation, and submersed macrophytes in large (5-7 ha) experimental wetlands in Delta Marsh, Manitoba, Canada. In general, the effects of Common Carp on water quality were similar to those encountered in systems undergoing cultural eutrophica- tion. With increasing densities of Common Carp, water column nutrient concentrations, suspended solids, and chlo- rophyll a increased while dissolved oxygen concentrations, submersed macrophyte density, and photic depth decreased. The wetlands did not become noticeably more turbid, contrary to our expectation, probably due to the mitigating effects of dense submersed macrophyte beds, and to high water color that likely prevented phytoplankton from flourishing.

This paper documents and characterizes a rare form of boreal wetland associated with the nests of whooping cranes, an endangered species. Diatom ponds are found in wetlands in association with bulrush marshes. They are shallow ( 1000 m in diameter, may evaporate down to diatom muck by late summer, are strongly influenced by dissolution of gypsum, and are circumneutral to alkaline and high in sulphates. Aquatic macrophytes are few. Pond waters are clear, and the predominant primary producers are a benthic diatom community that gives the ponds a characteristic yellow color (viewed from the air). As the diatom ponds dry, they change color from yellow to pink (when water table is at the surface) to cream (due to a dried diatom and sulphate crust). Diatomaceous earth or sedimentary peat underlies the ponds, which exist in a dynamic relationship with bulrush marshes, wet meadows, fens, and bogs. In the U.S. wetland classification system, diatom ponds fit most nearly within the palustrine, unconsolidated bottom, aquatic bed type. In the Canadian wetland classification system, the diatom ponds might fit in the marsh/shallow open water complex, with a new distinction at the type level. The association between nesting cranes and diatom ponds may be due to a combination of factors such as long sight lines for detection of predators, the proximity of bulrush (their favored nesting material), and use of the ponds for feeding.

Enclosures deployed in Delta Marsh, Canada, were treated with inorganic N and P either as two discrete additions (pulse) or as 29 smaller additions (press) comprising the same cumulative nutrient load over a three-month period. No effects on photosynthesis by phytoplankton, epiphyton or epipelon were detected. Similarly, phytoplankton and epipelon biomass was unaffected by any treatment. However, epiphyton and metaphyton biomass increased significantly. Absent from controls except after macrophyte senescence, metaphyton represented > 80 % of total algal biomass and total algal P in treated enclosures. No differences in metaphyton biomass between press and pulse treatments were observed although its composition varied; diffuse masses of Cladophora developed in pulse enclosures whereas floating carpets of Enteromorpha occurred in press enclosures. The latter decreased water column irradiance markedly, leading to premature macrophyte senescence. Sediment and metaphyton were probably the primary sinks for added nutrients. These results illustrate that nutrient enrichment can shift a stable epiphyton-dominant system (open wetland) to metaphyton dominance (sheltered wetland) if macrophytes remain sufficiently abundant to provide substratum for metaphytic algae. Development of the phytoplankton-dominant lake wetland state presumably occurs only when there are few other algal and macrophytic competitors for nutrients.

Bottom-up experimental manipulation of a wetland food web via press or pulse nutrient additions in Delta Marsh, Canada, demonstrated a differential response among primary producers and associated invertebrate grazers. Microinvertebrate grazers, dominated by Ceriodaphnia dubia, effectively depressed phytoplankton biomass in control, press, and pulse enclosures in the absence of fish predators. Similarly, microinvertebrate grazers increased in density in response to increased availability of periphyton on acrylic rods in both press and pulse nutrient treatments. Subsequently, proliferation of inedible filamentous green algae, in part as a consequence of size-selective herbivory, especially with the press nutrrient additions, led to a marked decline in grazer density. Macrophyte-associated invertebrates, mainly chydorid cladocerans, increased in abundance in parallel with macrophyte biomass changes and reduced epiphyton biomass through most of the season. Metaphyton shading (primarily in the press treatment) led to macrophyte decline and eventual decomposition, and substantial reduction in phytophilous invertebrate density. These grazer-algal interactions support the hypothesis of top-down control by grazers on algae (phytoplankton and epiphyton) as a regulatory mechanism in macrophyte-dominated aquatic ecosystems. The transition from epiphyton-dominated to metaphyton-dominated wetland is shown to be facilitated by herbivory, nutrient addition, and continuous availability of nutrients.

The quantitative contribution of benthic (periphytic) and planktonic algae to primary production in prairie wetlands is largely unknown, as is their response to the fluctuations in water level that characterize such systems. We measured the biomass (chlorophyll-a m−2 of wetland area) of phytoplankton, epipelon, epiphyton, and metaphyton in Delta Marsh, Manitoba as part of a five-year study in which diked, drawn down cells were reflooded to the normal level of the wetland, or to a depth 30 cm or 60 cm deeper. Our objective was to investigate the effects of flooding depth on algal biomass and the relative contributions by each of the four algal assemblages. Floating metaphyton mats flourished in all cells after flooding, contributing about 87% of total algal biomass. Epiphytes contributed 11% of biomass, and epipelon and phytoplankton each contributed 1%. Emergent macrophyte density was reduced by flooding, leading to increases in open water area. The wetland cells changed gradually over the study period from an early “open wetland” to a “sheltered wetland.” In late stages of the study, phytoplankton became more abundant as the cells proceeded to a “lake wetland” state.

There have been few measurements of primary productivity by benthic (periphytic) and planktonic algae in prairie wetlands so their quantitative importance relative to other primary producers is largely unknown. We measured the daily productivity (inorganic carbon assimilation per m2 of wetland area) of phytoplankton, epipelon, epiphyton, and metaphyton in ten wetland cells in Delta Marsh, Manitoba over a five-year period. Water levels in the cells were manipulated so that some cells had normal water levels for the wetland, while water depths increased 30 cm or 60 cm in other treatments. With increasing water depth, phytoplankton productivity increased while that of epipelon, epiphyton, and metaphyton decreased. Metaphyton was the largest contributor to total algal productivity (70%), followed by epiphyton (23%), phytoplankton (6%), and epipelon (1%). Phytoplankton had the highest photosynthetic efficiency (C assimilated per unit chlorophyll), despite being a minor contributor to total productivity. Variations in P-I parameters (α, β, Ik, and Pmax) were considerable, possibly due to temporal and spatial fluctuation in the abiotic environment. Algal productivity was comparable to that of submersed and emergent macrophytes, suggesting that algae are probably important resources in supporting food webs in prairie wetlands.

Traditional techniques for algal enumeration on substrata may ignore variation along microenvironmental gradients. To examine microdistributional patterns of diatoms on such surfaces, topographically simple, nutritionally inert artificial substrata were positioned in a duckweed-covered canal and in the littoral zone of a prairie lake. After a period of colonization, substrata were sampled using a surficial peel technique along a short section suspected to traverse sharp microenvironmental gradients of irradiance and nutrient concentration. At both sites, significant horizontal and vertical microheterogeneity in diatom species abundance was observed on a single substratum. A zonation of diatom species occurred with depth in the duckweed mat; Achnanthes hungarica, an apparently host-specific taxon, was distributed mostly in the leaf zone of the mat. Join-count analysis of a peel sample from the lake demonstrated that the major diatom taxa were significantly more abundant on some parts of the substratum than...

Three small ponds in the boreal forest of southern Manitoba were treated with an aerial application of 2.1 kg/ha glyphosate. Two of the ponds had been treated the preceding year with 0.9 kg/ha glyphosate, whereas the third was previously untreated. Foliage samples of plants bordering the ponds were collected immediately after treatment, and water and sediment samples were collected over a period of 265 d after treatment. Samples were analyzed for glyphosate and its first metabolite, aminomethylphosphonic acid (AMPA). We found that glyphosate dissipated rapidly from the surface waters of all ponds (dissipation half-lives of 3.5-11.2 d). AMPA residues were detected in water samples during the first 14 d after treatment, suggesting that herbicide degradation was occurring in the water column. However, not all applied herbicide was accountable in residues in the water. Glyphosate and AMPA increased in sediment samples to day 36, suggesting that sediment adsorption was a major sink for the herbicide. Glyphosate dissipation from the water column was biphasic, with a rapid initial phase followed by a slower phase. We hypothesize this was due to herbicide sorption and partitioning between suspended particulate matter and bottom sediments. As was found after the first pond treatment, glyphosate dissipation was slower in chemically alkaline ponds than in a more dilute pond, suggesting that herbicide complexation with ions in solution may be a significant factor affecting the rate of dissipation in standing water.

Chemically inert, cylindrical rods positioned in the littoral of two eutrophic Alberta lakes supported higher periphytic algal biomass (measured as total chlorophyll a) than nearby morphologically similar culms of Scirpus validus Vahl. during most of the summer. Upon initiation of macrophyte senescence, biomass on the two substrata became more similar. Experiments were conducted to investigate the basis for these observations. Whole extracts of intact vegetative Scirpus culms had no effect on periphyton photosynthesis, suggesting that the natural substrata do not produce water-soluble allelochemicals. Various modifications of the rod surfaces (roughening, wax coating, wax color) were used to test whether surficial properties of Scirpus culms influenced periphyton accumulation. Roughened rods supported levels of biomass similar to those of smooth rods, and both substrata developed structurally complex periphyton communities. Rods covered with paraffin wax had periphyton communities that were lower in biomass and structurally more simple than those on un-coated rods or on Scirpus culms. Coloring of the wax coating had no consistent effect on periphyton accumulation. We hypothesize that the hydrophobic cuticle on actively growing Scirpus culms retards the development of precursors for attachment by periphytic algae. Upon senescence of the culm and loss of epidermal integrity, colonization of culm surfaces by periphytic algae may occur in a manner similar to that on artificial substrata.

This laboratory study examined the interactions between an algal species found in wetlands (Selenastrum capricornutum) and two agricultural pesticides (atrazine and lindane). Pesticide additions had a positive effect on the chlorophyll a concentrations of the treatments. The presence of algae decreased the aqueous persistence of both pesticides. It is speculated that the algae either provided sites for pesticide sorption or facilitated pesticide degradation.

Recent fisheries data from northern Manitoba indicates that the Common Carp (Cyprinus carpio) has extended the northern limit of its range. Additionally, it also appears that carp have invaded and established viable populations in the Manitoba portion of the Churchill River. Habitat degradation and altered flow regimes as result of hydroelectric development in northern Manitoba may have facilitated the expansion of carp in the region.

A simple surficial peel technique using adhesive tape was developed for quantitative removal of haptobenthic diatom communities from topographically simple substrata. The method combines high removal efficiency with low peel distortion, permitting the use of spatial statistics to test whether populations are distributed in the peel randomly or form aggregated or uniform patterns. Using this technique, the microdistribution of Cocconeis placentula Ehr. on a smooth acrylic rod was examined. Using conventional nearest neighbor analyses, a clonal population of C. placentula. characterized by an indentation of the value margin, was significantly aggregated, whereas the overall C. placentula population was uniform or aggregated depending on whether the method of analysis allowed for cell size. Using refined nearest neighbor analysis, the indented population was aggregated, and the overall population was random at distances greater than cell size. The results suggest that the indented clone was weakly motile following cell division and that its directional bearing was random.