Molecular genetic data reveal hybridization between Typha angustifolia and Typha latifolia across a broad spatial scale in eastern North America

A recent increase in the abundance of cattails (Typha spp.) in North American wetlands has been anecdotally linked with hybridization between Typha latifolia and Typha angustifolia. In this study, we used molecular genetic markers (microsatellites) to investigate whether the hybrid lineage (Typha × glauca) is restricted to The Great Lakes region, or exists across a much broader spatial scale. We also investigated the possibility of backcrossing and genetic introgression in natural populations. Parental species could be distinguished from one another based on the distribution of alleles at six microsatellite loci. Species identification based on genetic data corresponded well with species identifications based on leaf width, a key morphological trait that can distinguish the two parental species. We found that hybrids occur in Ontario, Quebec, New Brunswick, and Nova Scotia, but we did not detect hybrids in Maine. F₁s are more abundant than backcrossed or intercrossed hybrids, although we also found evidence of backcrossing, particularly in Ontario. This indicates that hybrids are fertile, and are therefore potential conduits of gene flow between the parental species. Further work is needed to determine whether T. × glauca is particularly successful in the Great Lakes region relative to other areas in which the two parental species co-exist, and to assess whether introgression may lead to increased invasiveness in the species complex.     

Typha glauca Godron and its parental plants in Poland: taxonomic characteristics

Natural interspecific hybridization between Typha latifolia L. and Typha angustifolia L. was analyzed by morpho-anatomical and molecular methods to determine whether the hybrid Typha glauca Godr. is present in Poland and to identify the best diagnostic traits for its identification. Eighty-three samples of the Typha species were collected. Nine random amplified polymorphic DNA (RAPD) primers provided 12 fragments specific for T. angustifolia and eight fragments specific for T. latifolia. DNA of all sampled individuals was analyzed with 20 diagnostic RAPD markers. The morpho-anatomical variability of T. glauca F₁ was found to be quite similar to that observed in parental plants. All of the 41 traits examined in the hybrids overlapped with those observed in the parents, however, the hybrids were visibly closer to T. angustifolia than to T. latifolia. The most discriminate characteristics were the length and pedicel width, as well as the epidermal cell thickness located above vascular bundles in leaf blades. Moreover, preliminary observations of seed sculpture showed that the length of testa cells could also be used to identify T. glauca. Clusters and the hybrid index (for molecular and morphological data) were highly coincident and support the hybridization hypothesis.     

Effects of experimental harvesting of an invasive hybrid cattail on wetland structure and function

Invasive plants, such as the hybrid cattail Typha × glauca, can reduce biodiversity and alter the ability of wetlands to provide critical ecosystem services, including nutrient cycling and carbon storage. Several approaches have been used to reduce Typha dominance and restore invaded wetlands, but long‐term studies assessing benefits of these restoration efforts are limited. A previous study demonstrated that aboveground harvesting of Typha × glauca stems and litter reduced Typha dominance 2 years post‐treatment in a Great Lakes coastal wetland. In the current study, we extended monitoring of experimental aboveground Typha harvest to 4 years post‐treatment and added assessments of treatment effects on soil nutrients, carbon emissions, and microbial community composition. Aboveground harvest treatment resulted in a dramatic reduction in Typha litter cover that persisted for 4 years, increased soil temperature, and increased abundance of the native plant genus Carex. However, aboveground harvest treatment did not significantly reduce Typha abundance, nor did it have significant effects on soil nutrient concentrations, carbon fluxes, or the taxonomic composition of soil microbial communities. We did observe differences in bacterial community composition between plots based on time since Typha invasion, which may indicate some legacy effects of Typha invasion. At the scale of this experiment (4 × 4 m plots), our results indicate that a single aboveground removal of Typha × glauca is not sufficient to restore a heavily invaded freshwater wetland ecosystem, and that periodic harvesting of Typha stems and litter may be required to maintain native plant abundance.     

Gas chromatography mass spectrometry based profiling of alkyl coumarates and ferulates in two species of cattail (Typha domingensis P., and Typha latifolia L.)

Several long-chain n-alkyl coumarates and ferulates were identified in cattails (Typha domingensis and Typha latifolia) from the Florida Everglades. Characterization of these compounds was achieved based on the interpretation of mass spectra obtained by GCMS as their trimethylsilyl ether derivatives, comparison with published mass spectra and available standards. Both n-alkyl p-coumarates and n-alkyl ferulates were identified in roots and leaves of both Typha species, featuring unique distribution patterns and differences between leaf and root biomass. For both Typha species, roots have higher concentrations and a much greater diversity of n-alkyl p-coumarates and ferulates but with different side chain carbon numbers ranging from C₁₄ to C₂₈. Typha domingensis leaves only contained n-alkyl ferulates with traces of n-alkyl p-coumarates, while both types of compounds were present in Typha latifolia leaf material. These chemicals were not found in the other dominant wetland vegetation, which suggests their potential for application as phytochemical tracers of fresh cattail-derived organic matter in the Everglades ecosystem.     

Analysis of pollen proteins of Typha species in relation to identification of hybrids

Hybridization studies have been carried out with Typha angustifolia, T. latifolia, T. shuttleworthii and T. minima. All combinations, except those with T. minima, were successful. The hybrid $\text{T. latifolia (♀) × T. angustifolia (♂)}$ has been obtained after 5 attempts involving hundreds of pollinations. The pollen proteins of the parental as well as the F₁ generation have been examined by isoelectrofocusing (IEF). The proteins from each species and each hybrid form displayed a distinct and constant pattern. The pollen protein profile thus represents a new, quite easily accessible character by which F₁ hybrids between the species studied can be unequivocally identified, whereas the morphological criteria described in the literature to distinguish intermediate forms is insufficient for this purpose.     

Evaluation of AFLP markers to reveal genetic diversity in Typha

We investigated to what extent DNA-markers can assist species determination in the genus Typha. A set of AFLP markers was used to discriminate samples of the species Typha latifolia and Typha angustifolia collected in Flanders (North Belgium). The T. latifolia samples formed a compact cluster while the T. angustifolia samples were divided into smaller groups. It was not clear whether interspecific hybrids or higher levels of diversity present in the T. angustifolia dataset could account for this. As in previous surveys, using isozyme and VNTR markers, AFLP markers revealed an almost complete lack of genetic variation in Flemish T. latifolia. Despite the low degree of diversity, a significant level of genetic differentiation was found between the T. latifolia samples originating from different river basins. Whether this differentiation has any ecological relevance remains to be investigated. The methodology applied was not able to detect clonal reproduction in T. latifolia. Probably, the low levels of diversity present in this species can account for this, indicating that the usefulness of the methodology applied depends on the level of diversity present in the species studied.     

Application of the index of marsh bird community integrity to coastal wetlands of Georgian Bay and Lake Ontario,Canada

Ecological indicators have gained increasing attention within the scientific community over the past 40 years. Several taxonomic groups have been used successfully as indicators including most prominently fish, invertebrates, plants, and birds because of their ability to indicate environmental changes. In the Laurentian Great Lakes region, there has been recent concern over the applicability of using indicators on a basin-wide scale due to species range restrictions and lake-based differences. The objective of this study was to determine the ability of the Index of Marsh Bird Community Integrity (IMBCI) to indicate land use disturbance surrounding coastal marshes of Georgian Bay and Lake Ontario. To meet this objective, we surveyed birds and vegetation at 14 marshes in Georgian Bay (low land use disturbance) and Lake Ontario (high land use disturbance). Even though Lake Ontario marshes were surrounded by significantly more altered land than Georgian Bay marshes, and had poorer water quality, we found significantly fewer birds in Georgian Bay marshes (mean = 8.2) compared to Lake Ontario (mean = 13.7) and no significant difference in IMBCI scores. This inconsistency could be due to vegetation differences affecting the strength of the index, because Georgian Bay wetlands had significantly more bulrush (Schoenoplectus spp.) and floating vegetation, while Lake Ontario wetland vegetation was taller and cattail-dominated (Typha spp.). These findings suggest that the IMBCI may not be useful on a basin-wide scale in the Great Lakes region in detecting human disturbance surrounding wetlands.     

Responses of wetland plants to ammonia and water level

Constructed wetland systems receiving animal wastewater may enhance water quality when designed, operated, and maintained properly. In the case of wetlands designed to treat animal waste, system effectiveness may be limited by high ammonia concentrations and inundation, conditions that can adversely affect macrophytic vegetation. We conducted a 4-month greenhouse experiment to assess the impact of ammonia concentration and water level on plants commonly used in constructed wetlands for treating animal waste. We examined the effects of ammonia concentration (0, 50, 100, 200 and 400 mg/l) on the growth and biomass production of Juncus effusus, Sagittaria latifolia, Schoenoplectus tabernaemontani, Typha angustifolia, and Typha latifolia. We also explored interactions between ammonia concentration (0, 50, 100, 200 and 400 mg/l) and water level (flooded and nonflooded conditions) for S. tabernaemontani and T. latifolia. We found that ammonia levels in excess of 200 mg/l inhibited growth for J. effusus, S. latifolia, and T. latifolia after a period of weeks, and levels in excess of 100 mg/l similarly inhibited growth for S. tabernaemontani. Ammonia levels in the range studied had an ambiguous effect on T. angustifolia. Affected species demonstrated similar fertilization/inhibition responses to increased ammonia, but important differences were noted between species. Flooded conditions of 10 cm did not significantly increase ammonia toxicity to S. tabernaemontani or T. latifolia. Our results emphasize the need for careful consideration of the species used in treatment wetlands, and suggest that management of ammonia concentration may enhance plant growth and system function.     

Comparison of created and natural freshwater emergent wetlands in Connecticut (USA)

Five three- to four-year old created palustrine/emergent wetland sites were compared with five nearby natural wetlands of comparable size and type. Hydrologic, soil and vegetation data were compiled over a nearly two-year period (1988-90). Created sites, which were located along major highways, exhibited more open water, greater water depth, and greater fluctuation in water depth than natural wetlands. Typical wetland soils exhibiting mottling and organic accumulation were wanting in created sites as compared with natural sites. Typha latifolia (common cattail) was the characteristic emergent vegetation at created sites, whereas a more diverse mosaic of emergent wetland species was often associated with Typha at the natural sites. Species richness was slightly higher in created (22–45) vs. natural (20–39) wetlands, but the mean difference (33 vs. 30) was not significant. Nearly half (44%) of the 54 wetland taxa found at the various study sites were more frequently recorded at created than natural wetlands. The presence of mycorrhizae in roots of Typha angustifolia (narrow-leaved cattail) and Phragmites australis (common reed) was greater at created than natural wetlands, which may be related to differential nutrient availability. Wildlife use at all sites ranged from occasional to rare, with more sightings of different species in the natural (39) than created (29) wetlands. The presence of P. australis and introduced Lythrum salicaria (purple loosestrife) may pose a threat to future species richness at the created sites. One created site has permanent flow-through hydrology, and its vegetation and wildlife somewhat mimic a natural wetland; however, the presence of P. australis and its potential spread pose an uncertain future for this site. This study suggests the possibility of creating small palustrine/emergent wetlands having certain functions associated with natural wetlands, such as flood water storage, sediment accretion and wildlife habitat. It is premature to evaluate fully the outcome of these wetland creation efforts. A decade or more is needed, emphasizing the importance of long term monitoring and the need to establish demonstration areas.     

Effects of flooding regime on wetland plant growth and species dominance in a mesocosm experiment

Flooding regimes are a primary influence on the wetland plant community. Human-induced disturbance often changes the duration and frequency of flooding in wetlands, and has a marked influence on wetland plant composition and viability. Comprehensive studies of the environmental thresholds of wetland plants are required for the development of proper practices for wetland management and restoration after hydrological disturbance. This study provides a quantitative assessment of the establishment, growth, and community shifts in dominance of three emergent plant species (Scirpus tabernaemontani, Typha orientalis, and Zizania latifolia) typical of South Korean wetlands, under five hydrological regimes (waterlogged, low-level standing water, high-level standing water, intensive periodic flooding, and intermittent flooding) over four growing seasons. A mesocosm experiment was conducted in the campus of Seoul National University, South Korea. The number and biomass of shoots of Z. latifolia responded positively to increased water level and flooding frequency, while that of the other plants did not. Zizania latifolia outcompeted S. tabernaemontani and T. orientalis irrespective of hydrological regime. This study suggests that Z. latifolia can outcompete the other two macrophytes in the field. This study will improve our ability to predict the dynamics of wetland vegetation and so facilitate the formulation of wetland management and restoration strategies.     

Composition and dynamics of wetland seed banks on Mount St. Helens, Washington, USA

The 1980 eruption of Mount St. Helens deposited new substrates upon which wetlands are now developing. We collected soil from five wetlands south of Spirit Lake, Mount St. Helens, Washington, to examine the seed banks. Seedling emergence density in the top 5 cm was highly variable, and ranged from (mean±s.d.) 15,700±15,200 to 38,000±31,500 per m². Seedling emergence from soil at 5 to 10 cm depth varied from 800±600 to 18,000±24,800 per m², and averaged 1/3 as many seeds as the surface. The high proportion of buried seeds may be due to continuing deposition of upland sediments. We identified 17 taxa from the wetland soil samples withEpilobium ciliatum, Juncus bufonius, Agrostis exarata andJuncus ensifolius being the dominant species. Wetland vegetation was dominated byEquisetum arvense, Salix sitchensis, Typha latifolia and the four dominant species in the seed bank. Correlations between vegetation and seed bank were not significant for four of the five wetlands, and the dominance byTypha latifolia in two wetlands contributed to the low correlations. Thus, vegetation of these early successional wetlands generally was not similar to seed bank composition. Canonical correspondence analysis was used to relate soil parameters to vegetation and seed bank data. The vegetation was correlated primarily with soil particle size and secondarily to water temperature, while the seed bank was correlated to pH, texture and temperature.     

Multigenerational outbreeding effects in Chinook salmon (Oncorhynchus tshawytscha)

Outbreeding, mating between genetically divergent individuals, may result in negative fitness consequences for offspring via outbreeding depression. Outbreeding effects are of notable concern in salmonid research as outbreeding can have major implications for salmon aquaculture and conservation management. We therefore quantified outbreeding effects in two generations (F₁ hybrids and F₂ backcrossed hybrids) of Chinook salmon (Oncorhynchus tshawytscha) derived from captively-reared purebred lines that had been selectively bred for differential performance based on disease resistance and growth rate. Parental lines were crossed in 2009 to create purebred and reciprocal hybrid crosses (n = 53 families), and in 2010 parental and hybrid crosses were crossed to create purebred and backcrossed hybrid crosses (n = 66 families). Although we found significant genetic divergence between the parental lines (F_ST = 0.130), reciprocal F₁ hybrids showed no evidence of outbreeding depression (hybrid breakdown) or favorable heterosis for weight, length, condition or survival. The F₂ backcrossed hybrids showed no outbreeding depression for a suite of fitness related traits measured from egg to sexually mature adult life stages. Our study contributes to the current knowledge of outbreeding effects in salmonids and supports the need for more research to better comprehend the mechanisms driving outbreeding depression.     

Litter decomposition in created and reference wetlands in West Virginia,USA

Large amounts of resources have gone into wetland mitigation in recent years; however, it is still unclear whether wetland function is being replaced along with wetland area. Litter decomposition is linked to numerous wetland functions. In this study, we measured plant litter decomposition potential over 12 months in 8 created and 8 reference wetlands located in the Allegheny Mountains of West Virginia, USA. Broadleaf cattail (Typha latifolia L.) litter bags were placed in each wetland and collected at 3 month intervals. Linear decomposition rate constants and percent mass remaining were similar between wetland types (created and reference) and among Cowardin classifications (palustrine: unconsolidated bottom, aquatic bed, emergent, and scrub/shrub). Created wetland age was not correlated with decomposition potential. Our study found that created wetlands had similar litter decomposition potential as reference wetlands indicating that similar processes are likely acting upon litter decomposition within both natural and created wetlands.     

Anomalies of broad-leaved cattail (<Emphasis Type="Italic">Typha</Emphasis> L., Typhaceae) in a small anthropogenic pond of the Upper Volga basin

An increased anthropogenic impact on the hydrophilic ecosystems of technogenic ponds of the Volga–Caspian basin has enhanced the migration of Typha latifolia L. and closely related species. Due to backcrossings and anomalies among bractless sections of the genus Typha, new morphological traits have been formed in T. latifolia via the stage of a nonspecific form development. Morphological anomalies revealed in an association of Typhetum latifoliae Soó 1927 of a small anthropogenic pond in the Yaroslavl region have been studied.     

Intercontinental dispersal of Typha angustifolia and T. latifolia between Europe and North America has implications for Typha invasions

The full effects of biological invasions may be underestimated in many areas because of cryptogenic species, which are those that can be identified as neither native nor introduced. In North America, the cattails Typha latifolia, T. angustifolia, and their hybrid T. × glauca are increasingly aggressive invaders of wetlands. There is a widespread belief that T. latifolia is native to North America and T. angustifolia was introduced from Europe, although there has so far been little empirical support for the latter claim. We used microsatellite data and chloroplast DNA sequences to compare T. latifolia and T. angustifolia genotypes from eastern North America and Europe. In both species, our data revealed a high level of genetic similarity between North American and European populations that is indicative of relatively recent intercontinental dispersal. More specifically, the most likely scenario suggested by Approximate Bayesian Computation was an introduction of T. angustifolia from Europe to North America. We discuss the potential importance of our findings in the context of hybridization, novel genomes, and increasingly invasive behaviour in North American Typha spp.     

Synergistic impact of water level fluctuation and invasion of Glyceria on Typha in a freshwater marsh of Lake Ontario

The effects of multiple stressors on the native Typha marsh community (mainly Typha latifolia) were examined using historical records of water levels, human census population, and field vegetation maps. Percent cover of the major plant species was estimated in a GIS, and the percent cover of Typha was related to changes in water level, human population growth, and percent cover of exotic Glyceria maxima and invasive Phragmites australis. Water level fluctuation was the major natural disturbance and it alone accounted for 88% of the variation in Typha. After partitioning out the effect of water level, both human population growth and the presence of exotic species were still significantly related to the decline of native Typha. We suggest that multiple stressors interact with each other to influence changes in native Typha community and cause greater detrimental impact. An important implication of our results is that projected water level decline due to climate change may not necessarily favor the restoration of a desirable native marsh because of the presence of other disturbances such as exotic and invasive species and altered nutrient regime.     

Interspecific differences in radial oxygen loss from the roots of three <Emphasis Type="Italic">Typha</Emphasis> species

A comparison was made of the radial oxygen loss (ROL) from the roots of three Typha species, Typha latifolia L., Typha orientalis Presl and Typha angustifolia L., which resemble each other in morphology. ROLs were evaluated in the laboratory for seedlings of T. orientalis and T. angustifolia in order to compare them with the ROL value for T. latifolia obtained in our previous study. Measurements were conducted using the highly oxygen-sensitive anthraquinone radical anion as an oxygen indicator, which enabled us to simulate the natural conditions in which the oxygen released from the root is immediately consumed by the soil. Among the three Typha species, the ROL was the highest in T. angustifolia, followed by T. latifolia and T. orientalis. Illumination significantly enhances the ROL of T. orientalis, and this effect was also observed for T. latifolia in our previous study, whereas it did not affect the ROL of T. angustifolia. These results indicate that ROL differs significantly between species, even among members of the same genus that are similar in morphology.     

Longitudinal trends and discontinuities in nutrients,chlorophyll, and suspended solids in the Upper Mississippi River: implications for transport,processing, and export by large rivers

We evaluated habitat changes of tributary (drowned river mouth) wetlands in the upper St. Lawrence River with analysis of pre-and post-regulation water levels and historical vegetation reconstruction from aerial photographs. In addition, the germination response of transplanted wetland soil was compared to understand responses to moist versus saturated hydrology. Typha stem density was sampled in reference sites under the influence of water-level regulation by the International Joint Commission (IJC) and compared to treatment sites where installed control structures held levels (<0.7 m) higher. Major hydrologic changes due to regulation included a reduction of inter-annual variability with a reduction in peak levels and periodic lows, leading to a dampening of 30–40 year water-level cycles. Wetland photo interpretation indicated that flooded and mixed habitat categories were apparent at all sites for pre-regulation in 1948, but post-regulation photos (1972 and 1994) showed encroachment of robust emergent (Typha angustifolia, T. latifolia, and T. x glauca) in these habitats. Vegetation surveys (7 years, 2001–2007) indicated that reference and treatment sites were dominated by Typha, but mean stem densities were not statistically different. Typha stem density, however, declined in response to decreased summer water level. Periodic summer low water levels coupled with higher winter levels (that promote muskrat activity) were hypothesized to have the greatest effect on reducing Typha density. Seed-bank analysis indicated that a greater diversity of plant species germinated in mesic (moist) conditions than in the saturated treatment (flooded), where Typha was the dominant seedling component. Altered hydrologic regimes and invasive Typha have had a substantial effect on habitat structure within coastal wetlands and inferences from local management of levels provide useful guidance for future system-wide regulation.     

Organic matter,anion, and metal wastewater treatment in Damyang surface-flow constructed wetlands in Korea

Surface-flow wetlands constructed with Acorus and Typha plants, connected to a wastewater treatment plant, were investigated with respect to organics (dissolved organic matter), anions (nitrate, sulfate, and phosphate), metals (Cu, Ni, Zn, Fe, and Mn), and metalloids (As). The results of the research indicated: (1) effluent organic matter (EfOM), based on dissolved organic carbon (DOC), was not efficiently removed by the wetlands. However, the hydrophobic, transphilic, and hydrophilic EfOM fractions varied throughout the wetlands, as identified by XAD-8/4 resins. (2) Nitrate, as compared to sulfate and phosphate, was efficiently removed, especially in the Typha wetland pond that had long retention time, under anoxic condition. (3) Most of the heavy metals were ineffectively removed via the wetland ponds. However, the iron concentration increased in the Typha wetland pond, which was probably due to its reduction under anoxic condition.