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Kurt P. Kowalski

Publications and source records attributed to Kurt P. Kowalski.

At least 19 recordsLinked to original sources
USGS2026

Towards a refined definition of “tidal influence” for the coastal wetland sciences

The astronomical tide relates to lunar (and to a lesser extent solar) influences on rising and falling water bodies, and is a key control of many coastal processes. However, tides manifest along coastal margins in different ways to muddle application beyond Sir Isaac Newton’s first descriptions. Here, we argue that tide, or specifically “tidal,” has not been adequately defined for the coastal wetland sciences to facilitate contemporary interdisciplinary distinction for rapidly changing coastlines and future climate adaptation planning. We provide a brief history of the tidal concept, and we describe tides in a diversity of uncommonly recognized marginal coastal environments. Common astronomical tide manifestations are described through hydrographic examples, then expanded to include those tidal environments exposed additionally to fluvial, meteorological (wind), or groundwater influences. Our expanded definition of “tidal” is intended to be a forward-looking construct as environments will inevitably change with sea-level rise, water extraction, and anthropogenic flow alteration. Our definition of wetland tidal influence, which we broaden, includes those “wetlands affected by astronomic water level fluctuations within coastally restricted environments causing frequent or infrequent surface inundation or groundwater tidal variation that affects the biogeochemistry of the soil (e.g., ion exchange capacity, oxygen state, mineralization processes)”. Astronomic water level fluctuations are often amplified or dampened by non-astronomical events, such as wind. Expanding the definition of what is considered tidal by the scientific community is critical for improved understanding of coastal wetland function and the suite of ecosystem services they provide people and society, including climate mitigation opportunity, management, and adaptation.

Wetlands↗
USGS2026

Loss and transformation of coastal wetlands due to global change in the conterminous United States: Past, present, and future

Coastal wetlands are being transformed by global change, impacting the ecological and societal benefits provided by these ecosystems. Synthesizing knowledge of historical and expected future transformations in coastal wetlands can help inform forward-looking planning and stewardship efforts. Here, we review anticipated future ecological transformations in coastal wetlands of the conterminous United States and contrast them with past transformations. We examine trends at the national scale but focus in detail on the following six wetland-rich regions: (1) Everglades, (2) Mississippi River delta, (3) Chesapeake Bay, (4) San Francisco Estuary, (5) Puget Sound, and (6) Great Lakes. This review is among the first to integrate and compare coastal wetland transformations in the Great Lakes with their oceanic counterparts. Between 1850 and 1970, wetland losses across the nation were high because coastal wetlands were viewed as flooded wastelands needing to be drained, filled, or excavated to make room for other land uses. Over the last 50 years, growing public and scientific appreciation of the ecological and societal benefits provided by coastal wetlands has fostered tremendous gains in wetland restoration and legal protection. Looking to the future, climate change and accelerated sea-level rise have become critical threats to coastal wetlands and are emerging as major drivers of ecological loss and transformation. This review synthesizes regional knowledge regarding past, present, and future changes to help coastal scientists, environmental managers, and the public better anticipate and prepare for future coastal wetland transformations due to climate change, accelerated sea-level rise, land-use change, and other aspects of global change.

conterminous United States↗
USGS2026

Comparative genomics reveals potential mechanisms of invasion in Phragmites australis (common reed)

Biological invasions are transforming ecosystems worldwide, yet the genomic bases enabling certain species to dominate new environments remain poorly understood. Phragmites australis , a widespread wetland grass with invasive and native subspecies co-occurring in North America, provides a powerful system to investigate genomic mechanisms of invasiveness. We generated independent chromosome-scale genome assemblies for invasive P. australis ssp. australis and co-occurring native ssp. americanus and used comparative genomic and transcriptomic analyses to identify lineage-specific innovations associated with invasive success. The invasive subspecies exhibits genomic novelties through functionally-biased single-copy orthologs, intronless genes, and subgenome expression asymmetry, along with a stress-ready basal transcriptome relative to the native subspecies. Following the removal of aboveground shoots (“cutback”), which measures the ability to recover from damage, the invasive subspecies undergoes stronger transcriptional reprogramming, increased shoot production, and higher biomass accumulation compared to the native. It also displays expansion of gene families and coordinately expressed gene modules that support resource mobilization, growth responses to light, and stress tolerance. Beyond Phragmites , comparative analyses across multiple grass genomes, including eight invasive species with related non-invasive species, revealed repeated expansion of gene families associated with abiotic stress tolerance and developmental regulation, suggesting convergent adaptive strategies in the grass family for invasive success. Together, these results demonstrate genomic architecture linked to invasion success and highlight potential targets for managing invasive grasses.

BioRxiv↗
USGS2026

Multi-year cut-to-drown management limits Phragmites australis growth, belowground resources, and rhizome viability in Great Lakes wetlands

The distribution and abundance of Phragmites in the Great Lakes coastal zone has expanded in part due to its unique ventilation physiology and its ability to take advantage of changes in lake levels over the past several decades. During an extended period of low lake levels in the early 2000s, Phragmites expanded into vast shallow water areas as lake bottoms were exposed. Many of those populations were able to persist when lake levels rose several years later. Here, we investigate a management strategy, known as cut-to-drown, that takes advantage of elevated water levels to effectively control Phragmites by cutting stems underwater, thereby drowning the plant and depleting its stored resources. We tested the impacts of cut timing and frequency on the effectiveness of the cut-to-drown strategy through a multi-year manipulative field study. After two seasons of treatments, we found a 92–99 % reduction in stem density, depending on cut timing. Carbohydrate reserves in rhizomes declined 75–92 %, such that rhizome viability was reduced by 73–100 %, depending on cut timing. We found that cutting continuously (every 2–3 weeks) throughout two growing seasons was the most effective way to implement cut-to-drown but provide evidence that less frequent cutting could produce similar results. Our study provides important evidence to inform best management practices for cut-to-drown. Particularly as lake level fluctuations become more frequent and extreme in the future, cut-to-drown could serve as a useful tool for limiting Phragmites’ ability to persist in high water environments.

Michigan, Ohio↗
USGS2026

Is "weediness" and "invasiveness" of weeds a function of the plant microbiome?

Over the past several decades, the extent to which microbes enhance plant development and health has become clearer; however, this has not been explored in terms of the aggressiveness and hardiness of weedy plants. In this review, we explore the hypothesis that many features of weeds and invasive plants are related to the activities of plant microbiomes. Microbes contribute to weed growth, fecundity, and fitness. They also play roles in soils, and in plants as endophytes, where they modulate plant development and protect the host from pathogens, insects, animals, and abiotic stresses. In addition, the adaptability and hardiness of weeds partly stem from the effects of endophytes on plant gene expression and genetic diversity. Weed control often involves multiple applications of herbicides or other treatments that can be costly and destructive. Weed and invasive plant control for agriculture and environment goes beyond monetary costs to negative impacts on people, animals and environment. However, with a more complete knowledge of the roles played by microbes, their symbiotic interactions may be altered to diminish aggressive traits less expensively and with fewer non target effects on environmental, human and animal health.

Grass Research↗
USGS2026

Abundance and movement patterns of fish accessing a reconnected Lake Erie coastal wetland: Insights from high-resolution sonar data

Coastal wetlands of the Laurentian Great Lakes are complex ecosystems that provide essential biological services, including providing habitat for a suite of fish species. As restoration efforts for these coastal wetlands increase, there is a need to characterize how well restored areas support the life histories of wetland, riverine, and lake fishes. Most traditional survey methods (e.g. 24hr trap netting, visual surveys) are implemented over periods of time that make it difficult to describe short-term fluxes in fish activity, especially in waters with difficult access or high turbidity. To address this gap, we used acoustic sonar technology to evaluate fish movement in a recently reconnected coastal wetland on the southern shore of western Lake Erie. Data collected over four years (2011-2014) indicated that the 10 ha wetland was continuously utilized by millions of fish, with discernible fluctuations in usage patterns observed on both daily and annual scales. These insights add to our understanding of how fish assemblages respond to restored coastal wetland habitats and can inform management decisions that may impact fish access (e.g. conduct management activities that may be disruptive to fish populations during periods of reduced utilization). Additional study of short-term fish movements using high-resolution sonar and other technologies will reveal patterns that may enhance the effectiveness of restoration and management efforts in Great Lakes coastal wetlands.

Lake Erie↗
USGS2025

Ecological thresholds and transformations due to climate change: The role of abiotic stress

An ecological threshold is the point at which a comparatively small environmental change triggers an abrupt and disproportionately large ecological response. In the face of accelerating climate change, there is concern that abrupt ecosystem transformations will become more widespread as critical ecological thresholds are crossed. There has been ongoing debate, however, regarding the prevalence of ecological thresholds across the natural world. While ecological thresholds are ubiquitous in some ecosystems, thresholds have been difficult to detect in others. Some studies have even concluded that threshold responses are uncommon in the natural world and overly emphasized in the ecological literature. As ecologists who work in ecosystems chronically exposed to high abiotic stress, we consider ecological thresholds and ecosystem transformations to be critical concepts that can greatly advance understanding of ecological responses to climate change and inform ecosystem management. But quantifying ecological thresholds can be challenging, if not impossible, without data that are strategically collected for that purpose. Here, we present a conceptual framework built upon linkages between abiotic stress, climate-driven ecological threshold responses, and the risk of ecosystem transformation. We also present a simple approach for quantifying ecological thresholds across abiotic stress gradients. We hypothesize that climate-driven threshold responses are especially influential in ecosystems chronically exposed to high abiotic stress, where autotroph diversity is low and foundation species play a prominent ecological role. Abiotic conditions in these environments are often near physiological tolerance limits of foundation species, which means that small abiotic changes can trigger landscape-level ecological transformations. Conversely, the alleviation of stress near thresholds can allow foundation species to thrive and spread into previously inhospitable locations. We provide examples of this climate-driven threshold behavior from four high-stress environments: coastal wetlands, coral reefs, drylands, and alpine ecosystems. Our overarching aim in this review is to clarify the strong relationships between abiotic stress, climate-driven ecological thresholds, and the risk of ecosystem transformation under climate change.

Ecosphere↗
USGS2025

Cell penetrating peptide-mediated delivery of gene-silencing nucleic acids to the invasive common reed Phragmites australis via foliar application

As a popular tool for gene function characterization and gene therapy, RNA interference (RNAi)-based gene silencing has been increasingly explored for potential applications to control invasive species. At least two major hurdles exist when applying this approach to invasive plants: (1) the design and screening of species- and gene-specific biomacromolecules (i.e., gene-silencing agents or GSAs) made of DNA, RNA, or peptides that can suppress the expression of target genes efficiently, and (2) the delivery vehicle needed to penetrate plant cell walls and other physical barriers (e.g., leaf cuticles). In this study, we investigated the cell-penetrating peptide (CPP)-mediated delivery of multiple types of GSAs (e.g., double-stranded RNA (dsRNA), artificial microRNA (amiRNA), and antisense oligonucleotide (ASO)) to knock down a putative phytoene desaturase ( PDS ) gene in the invasive common reed ( Phragmites australis spp. australis ). Both microscopic and quantitative gene expression evidence demonstrated the CPP-mediated internalization of GSA cargos and transient suppression of PDS expression in both treated and systemic leaves up to 7 days post foliar application. Although various GSA combinations and application rates and frequencies were tested, we observed limitations, including low gene-silencing efficiency and a lack of physiological trait alteration, likely owing to low CPP payload capacity and the incomplete characterization of the PDS-coding genes (e.g., the recent discovery of two PDS paralogs) in P. australis . Our work lays a foundation to support further research toward the development of convenient, cost-effective, field-deployable, and environmentally benign gene-silencing technologies for invasive P. australis management.

Mississippi, Ohio↗
USGS2024

The Metzger marsh restoration: A vegetation-centric look after 27 years

We investigated wetland vegetation before, during, and after dike construction at the Metzger Marsh project in western Lake Erie, which was designed to restore a 300-ha wetland that had been degraded following the loss of a protective barrier beach. A dike was constructed in 1995 to replace the function of the eroded barrier beach, but it contained a water-control structure to allow managed hydrologic connection to the lake. The control structure contained a fish passageway to allow movement of fish across the dike, while restricting entry of large common carp. Color-infrared aerial photos from project start in 1994 through 2010 (and 2022) were analyzed to track vegetation changes, and major vegetation types were sampled quantitatively. Drawdown of water levels in 1996 after dike construction elicited a response of mudflat species from the seed bank, as well as tree seedlings. Over half of the marsh was vegetated then and in subsequent years. The water-control structure was opened in 1998, and by 2000, invasive Phragmites australis had gained dominance. Most trees were eventually eliminated by herbicide treatment and flooding, and extent of Phragmites was reduced by management actions. Typha spp. and emergents Sagittaria latifolia and Schoenoplectus tabernaemontani became dominant by 2022. This restoration project increased habitat values for fish and wildlife; it also provided lessons for future projects on lands managed by multiple agencies with differing missions. More importantly, it showed that long-term monitoring data are critical for assessing wetland restoration projects and guiding management decisions.

Ohio↗
USGS2023

Phragmites management in high water: Cutting plants under water limits biomass production, carbohydrate storage, and rhizome viability

Invasion of Phragmites australis (common reed) in wetlands throughout North America, and particularly the Laurentian Great Lakes Basin, poses significant ecological problems. The extended period of low Great Lakes water levels from 2000 to 2013 created conditions for large expansions of Phragmites in the Great Lakes coastal zone. The following extended period of high water in the Great Lakes during late 2010’s, culminating in record high lake levels in 2020 allowed managers to take advantage of high water by using a cut-to-drown management strategy (i.e., cutting plants below the water surface to stop the flow of atmospheric gases) to control Phragmites populations. To examine the efficacy of a cut-to-drown control strategy, we conducted a controlled-greenhouse study that tested the effect of submergence and timing of cutting (early or late in growing season) on Phragmites growth and viability post treatment. To evaluate Phragmites growth and viability, we measured belowground biomass, rhizome non-structural carbohydrate content (NSC), and rhizome viability following a cut-to-drown treatment. Applying a cut-to-drown treatment reduced average belowground biomass production up to 99%, limited rhizome NSC content up to 83%, and inhibited rhizome viability, regardless of timing of cutting treatments. These results suggest that under high-water conditions, utilizing a cut-to-drown strategy has potential for being a useful control mechanism for Phragmites . However, further research is needed to determine to what extent these results will lead to sustained reductions in growth and viability under field conditions, where rhizome belowground biomass and storage capacity are much larger.

Wetlands Ecology and Management↗
USGS2023

Experimentally induced dieback conditions limit Phragmites australis growth

Phragmites australis is a cosmopolitan grass species common in wetland ecosystems across the world. In much of North America, the non-native subspecies of Phragmites threatens wetland biodiversity, hinders recreation, and is a persistent problem for natural resource managers. In other parts of the world, populations are in decline, as Reed Die-Back Syndrome (RDBS) plagues some Phragmites stands in its native range. RDBS is defined by a clumped growth form, stunted root and shoot growth, premature senescence, and shoot death. RDBS has been associated with a build-up of short-chain fatty acids (SCFAs) and altered bacterial and oomycete communities in soils, but the exact causes are unknown. To control invasive Phragmites populations, we sought to develop treatments that mimic the conditions of RDBS. We applied various SCFA treatments at various concentrations to mesocosm soils growing either Phragmites or native wetland plants. We found that the high-concentration SCFA treatments applied weekly induced strong significant declines in above- and belowground biomass of Phragmites . Declines were significant but slightly weaker in native species. In addition, soil bacterial abundance increased, diversity decreased, and bacterial community composition significantly differed following treatments, such that treated pots maintained a higher relative abundance of Pseudomonadaceae and fewer Acidobacteriaceae than untreated pots. Our results suggest that application of SCFAs to Phragmites can lead to stunted plants and altered soil bacterial communities similar to populations affected by RDBS. However, the lack of species-specificity and intensive application rate may not make this treatment ideal as a widespread management tool.

Michigan, Ohio↗
USGS2023

Optimization and application of non-native Phragmites australis transcriptome assemblies

Phragmites australis (common reed) has a cosmopolitan distribution and has been suggested as a model organism for the study of invasive plant species. In North America, the non-native subspecies (ssp. australis ) is widely distributed across the contiguous 48 states in the United States and large parts of Canada. Even though millions of dollars are spent annually on Phragmites management, insufficient knowledge of P . australis impeded the efficiency of management. To solve this problem, transcriptomic information generated from multiple types of tissue could be a valuable resource for future studies. Here, we constructed forty-nine P . australis transcriptomes assemblies via different assembly tools and multiple parameter settings. The optimal transcriptome assembly for functional annotation and downstream analyses was selected among these transcriptome assemblies by comprehensive assessments. For a total of 422,589 transcripts assembled in this transcriptome assembly, 319,046 transcripts (75.5%) have at least one functional annotation. Within the transcriptome assembly, we further identified 1,495 transcripts showing tissue-specific expression pattern, 10,828 putative transcription factors, and 72,165 candidates for simple sequence repeats markers. The identification and analyses of predicted transcripts related to herbicide- and salinity-resistant genes were shown as two applications of the transcriptomic information to facilitate further research on P . australis . Transcriptome assembly and selection would be important for the transcriptome annotation. With this optimal transcriptome assembly and all relative information from downstream analyses, we have helped to establish foundations for future studies on the mechanisms underlying the invasiveness of non-native P . australis subspecies.

PLoS ONE↗
USGS2023

Genetic analysis of North American Phragmites australis guides management approaches

Phragmites australis subsp. australis is an invasive and ecologically detrimental plant in multiple regions of North America. Its co-occurrence with the native subspecies, and multiple instances of hybridization, has created the need to differentiate Phragmites subspecies or haplotypes so that management can be appropriately targeted to the invader. We compiled a review of current genetic discrimination methods among the three Phragmites subspecies inhabiting the United States and Canada, and discussed how each method can contribute to control of the introduced subspecies while preserving the two endemic subspecies. We also discussed various control tools and the implications of Phragmites genetics for implementation. The Phragmites subspecies endemic to North America have environmental or infrastructure significance (e.g., habitat sustainability, biodiversity, storm surge and erosion protection). Thus, faster and more accurate differentiation among the endemic and introduced subspecies is needed. Additionally, more in-depth genetic information on Phragmites subspecies could support better management decisions, as well as the development of improved control treatments. This review highlights technologies and approaches currently available for genetic identification, recently collected genomic, transcriptomic and proteomic information, and implications for biological control and herbicide treatments.

Aquatic Botany↗
USGS2023

Estimating phosphorus retention capacity of flow-through wetlands

A Bayesian hierarchical modeling approach is introduced to pool data properly from multiple flow-through wetlands to estimate wetland-specific long-term phosphorus retention capacity. By pooling data from multiple wetlands, we overcome the difficulties in estimating the effectiveness of using constructed and natural wetlands for nutrient reduction. The Bayesian hierarchical modeling approach reduces estimation uncertainty by shrinking wetland-specific estimates towards the overall average of the same quantity from multiple wetlands, facilitating information sharing across sites, thereby reducing the demand on sample sizes from individual wetlands and avoiding several common pitfalls of using large data (i.e., from multiple systems) induced by Simpson's paradox. In this paper, we develop a sequential updating framework to alleviate the computational burden of compiling and modeling data from multiple wetlands. We then demonstrate the sequential updating process to estimate retention capacity of a suite of wetlands in Ohio, USA. A total of four wetlands, representing both natural and constructed wetlands, were used. The estimated total phosphorus retention capacities range less than 0.01 to well over 1 ton per year per system. As wetland restoration initiatives expand around the Laurentian Great Lakes and nationally, this model serves as an important initial step in developing tools to meet nutrient reduction goals and standards. Extending this work, we have developed a publicly accessible on-line open computation platform that can help natural resource specialists better plan for wetland efficacy in the future.

Ecological Engineering↗
USGS2023

A decision framework for the management of established biological invasions

In some cases, managing an established invasive species may do more harm to an ecosystem than allowing the invader to persist. Given limited resources available to land managers and the realities of conservation triage, we recognized the need for systematic guidance for management decisions made at the “late end” of the invasion curve. We gathered an interdisciplinary group of experts and practitioners to address the question of “under what circumstances is the active management of an established aquatic invasive species warranted?” Our working group identified three key dimensions to this question: (1) the efficacy of available management options; (2) the net benefits of management actions weighed against the null scenario of no control; and (3) the socio-ecological context that defines management goals, a manager’s ability to achieve said goals, and perceptions of management outcomes. These considerations were used to structure a consensus decision tree that supports a multi-criteria approach to decision-making. Our approach promotes interdisciplinarity and systems thinking and emphasizes the need to consider costs and benefits comprehensively, for example by considering the persistence or reversibility of impacts from both the invasive species and from efforts to suppress or eradicate it.

Facets↗
USGS2022

Turbidity and estimated phosphorus retention in a reconnected Lake Erie coastal wetland

Nearly all of the wetlands in the coastal zone of Lake Erie have been degraded or destroyed since the 1860s, and most of those that remain are separated from their watersheds by earthen dikes. Hydrologic isolation of these wetlands disrupts ecosystem benefits typical to Great Lakes coastal wetlands, particularly the ability to trap sediments and retain nutrients when inundated by runoff and lake water. High-frequency measurements of turbidity and discharge were taken in 2013 and 2014 to observe turbidity and water flow dynamics to estimate total phosphorus flux of a hydrologically reconnected diked wetland pool in the Crane Creek-Lake Erie wetland complex. Modeled estimates suggest the reconnected pool retained 8% of the total phosphorus loading in 2013 and 10% in 2014, which included short periods of phosphorus export to Lake Erie. Water flowing out of the wetland generally had lower turbidity than inflowing water, but flux in and out of the pool varied seasonally and was linked to changes in lake-levels, seiche dynamics, and weather conditions. More frequent storms, higher winds, and stronger seiches in the spring and fall created turbidity patterns that suggest more phosphorus retention than in summer or winter. Estimates suggest that phosphorus was released during the summer when higher lake levels and the absence of frequent storms, larger short-term seiche oscillations, and potentially soil oxygen availability were driving flux dynamics. This study demonstrated that reestablishing lake hydrology through reconnection of wetland pools can reduce loading and alter timing of delivery of total phosphorus to Lake Erie.

Ohio↗
USGS2022

Histochemical evidence for nitrogen‐transfer Endosymbiosis in non‐photosynthetic cells of leaves and inflorescence bracts of angiosperms

We used light and confocal microscopy to visualize bacteria in leaf and bract cells of more than 30 species in 18 families of seed plants. Through histochemical analysis, we detected hormones (including ethylene and nitric oxide), superoxide, and nitrogenous chemicals (including nitric oxide and nitrate) around bacteria within plant cells. Bacteria were observed in epidermal cells, various filamentous and glandular trichomes, and other non-photosynthetic cells. Most notably, bacteria showing nitrate formation based on histochemical staining were present in glandular trichomes of some dicots (e.g., Humulus lupulus and Cannabis sativa ). Glandular trichome chemistry is hypothesized to function to scavenge oxygen around bacteria and reduce oxidative damage to intracellular bacterial cells. Experiments to assess the differential absorption of isotopic nitrogen into plants suggest the assimilation of nitrogen into actively growing tissues of plants, where bacteria are most active and carbohydrates are more available. The leaf and bract cell endosymbiosis types outlined in this paper have not been previously reported and may be important in facilitating plant growth, development, oxidative stress resistance, and nutrient absorption into plants. It is unknown whether leaf and bract cell endosymbioses are significant in increasing the nitrogen content of plants. From the experiments that we conducted, it is impossible to know whether plant trichomes evolved specifically as organs for nitrogen fixation or if, instead, trichomes are structures in which bacteria easily colonize and where some casual nitrogen transfer may occur between bacteria and plant cells. It is likely that the endosymbioses seen in leaves and bracts are less efficient than those of root nodules of legumes in similar plants. However, the presence of endosymbioses that yield nitrate in plants could confer a reduced need for soil nitrogen and constitute increased nitrogen-use efficiency, even if the actual amount of nitrogen transferred to plant cells is small. More research is needed to evaluate the importance of nitrogen transfer within leaf and bract cells of plants

Biology↗