Laurentian Great Lakes Region Research Articles

Population Genetic Differentiation of Walleye (Sander vitreus) across the Eastern Highlands of the United States

Walleye is an important sportfish across eastern North America, is commercially fished in the Laurentian Great Lakes region, and has been introduced outside its native range. Thirty-eight Walleye populations within six watersheds across the Eastern Highlands and other portions of the native range were screened at eight microsatellite DNA loci to better understand evolutionary history and to inform fishery management and conservation efforts. Population genetic variation showed divergent assemblages of populations, respectively, living in the Mobile Bay, Mississippi River, Eastern Highlands (Tennessee, New, and Ohio Rivers), and Great Lakes drainages today. All estimates of effective numbers of breeding individuals were under 25, and all populations within all watersheds had ~15–20% inter-individual relatedness, likely attributable to the effects of both natural demographic processes and stocking. The extent of Eastern Highlands Walleye includes both the Ohio and Tennessee River basins.

Environmental DNA reveals the genetic diversity and population structure of an invasive species in the Laurentian Great Lakes

Environmental DNA (eDNA) has been established as a noninvasive and efficient approach to sample genetic material from aquatic environments. Although most commonly used to determine species presence and measure biodiversity, eDNA approaches also hold great potential to obtain population-level genetic information from water samples. In this study, we sequenced a panel of multiallelic microsatellite markers from filtered water and fish tissue samples to uncover patterns of intraspecific diversity in the freshwater Round Goby (Neogobius melanostomus) across their invaded range in the Laurentian Great Lakes region. Although we found that the concentration of nuclear eDNA is lower than mitochondrial eDNA, we nonetheless detected over two-thirds of all nuclear alleles identified from genotyped tissues in our eDNA samples, with the greatest recovery of common alleles in the population. Estimates of allele frequencies and genetic variability within and between populations were detected from eDNA in patterns that were consistent with individual tissue-based estimates of genetic diversity and differentiation. The strongest genetic differentiation in both eDNA and tissues exists in an isolation by distance pattern. Our study demonstrates the potential for eDNA-based approaches to characterize key population parameters required to effectively monitor, manage, or sustain aquatic species.

King rail (Rallus elegans) home range and microhabitat characteristics in western Lake Erie coastal marshes

The king rail (Rallus elegans) is a secretive marsh bird that is threatened or endangered in eight of nine states and provinces in the Laurentian Great Lakes (Great Lakes) region. Available survey data suggests that this species has undergone population declines across this region and these are believed to have been driven by habitat loss and degradation. An improved understanding of the amount and type of habitat king rails require during the breeding season at sites within the Great Lakes region would inform and improve progress toward conservation goals. During 2019-2021, we caught and radio-tagged 14 king rails in northwestern Ohio and southeastern Michigan within impounded coastal wetlands of western Lake Erie. We used radio telemetry to identify breeding season (May-August) home-range characteristics and third order habitat selection within home ranges (hereafter microhabitat). For the birds whose home range stabilized (N = 10), we found a mean home-range size of 8.8 ha (±1.63 [SE]; range = 1.9 to 15.8). We generated a classification tree to determine which habitat characteristics were associated with king rail presence within home ranges in our study. We found that vegetative density within home ranges was particularly associated with king rail presence. Phragmites australis was also associated with king rail presence, despite its invasiveness and negative ecological impacts in the region, and could be selectively maintained to benefit king rails. Our results suggest that managers may be able to provide microhabitat for king rails by maintaining water depths of 6 to 17 cm and by promoting native, robust vegetation in the genera Carex and Juncus. Our findings could help inform wetland managers and conservation planners in the Great Lakes region, particularly in western Lake Erie coastal marshes, of patch sizes, water depths, plant communities, and vegetative structure preferred by king rails.

Tribally-Led Consultation on the Ethical Use of Sedimentary Ancient DNA for a Culturally Important Plant: Manoomin, Psin, Zizania (Wild Rice)

Led by Native American resource managers, we have convened a working group across 20+ tribal entities in the north-central United States, with the goal of building consensus around the use of sedimentary ancient DNA (sedaDNA) to detect deep-past and recent populations of wild rice (manoomin in Ojibwe, psiŋ in Dakota, Zizania palustris and Z. aquatica) using lake sediment cores. Wild rice is of extremely high cultural and spiritual importance to many Indigenous people of the Laurentian Great Lakes region, as well as being a valuable traditional food and providing important habitat for waterfowl and other organisms. Because of its importance, any research involving wild rice must be tribally led, and outcomes designed to benefit the tribes (e.g., Matson et al. 2020). Wild rice is threatened by environmental degradation due to industrial processes and agriculture, so its protection can be a contentious regulatory and political issue in Minnesota, Wisconsin, and Michigan, involving tribal, state, and federal agencies. The wild rice paleorecord has tremendous potential for detecting and tracking past changes in wild rice distributions. Until recently, however, proxies for wild rice were either ineffective (pollen, seeds), or low-throughput and thus not scalable to region-wide use (phytoliths). SedaDNA would supplement Indigenous knowledge and Western scientific methods to inform conservation, management, designation for protection, and the enhancement of cultural and historical records. In this presentation, we will describe how we are synthesizing output from facilitated online meetings with and presentations to tribal resource managers into a white paper providing guidance from these sovereign Nations to academic researchers, agencies, and policymakers on restrictions on the utilization of sedaDNA of wild rice, the leadership roles tribal entities should take in all research, and tribal priorities for the application of this technique.

Community capacity and climate change in the Laurentian Great Lakes Region: the importance of social, human, and political capital for community responses to climate-driven disturbances

The Laurentian Great Lakes region in North America is experiencing climate-driven disturbances that threaten the public safety of the region and is forcing communities to respond. Communities vary in their ability to respond to these disturbances based on their existing capacities and access to resources, but responses in the region are uneven and create vulnerabilities to disasters. A virtual workshop was conducted to understand the community responses to climate-driven disturbances in the Great Lakes and identify the essential capacities for effective responses. Results show that the region as a whole has not responded adequately, and although the resources exist to respond, they are not adequately organized, and inequalities between urban and rural communities can exacerbate these challenges. Community capacities identified as critical for resilience include leadership, scientific knowledge, and connection to broader regional networks to access additional resources, but there are challenges with the complacency of some communities and deficiencies in mental health services.

Integrating invasive species risk assessment into environmental DNA metabarcoding reference libraries.

Environmental DNA (eDNA) metabarcoding has shown promise as a tool for estimating biodiversity and early detection of invasive species. In aquatic systems, advantages of this method include the ability to concurrently monitor biodiversity and detect incipient invasions simply through the collection and analysis of water samples. However, depending on the molecular markers chosen for a given study, reference libraries containing target sequences from present species may limit the usefulness of eDNA metabarcoding. To explore the extent of this issue and how it may be resolved to aid biodiversity and invasive species early detection goals, we focus on fishes in the well-studied Laurentian Great Lakes region. First, we provide a synthesis of species currently known from the region and of non-indigenous species identified as threats by international, national, regional, and introduction pathway-specific fish risk assessments. With these species lists, we then evaluate 23 primer pairs commonly used in fish eDNA metabarcoding with available databases of sequence coverage and species specificity. Finally, we identify established and potentially invasive non-indigenous fish that should be prioritized for genetic sequencing to ensure robust eDNA metabarcoding for the region. Our results should increase confidence in using eDNA metabarcoding for fisheries conservation and management in the Great Lakes region and help prioritize reference sequencing efforts. The ultimate utility of eDNA metabarcoding approaches will come when conservation management of existing fish communities is integrated with early detection efforts for invasive species surveillance to assess total fish biodiversity.

Local environmental conditions influence species replacement in Great Lakes interdunal wetland macroinvertebrate communities

Abstract Understanding the role of environmental filtering and spatial processes along environmental gradients in assembling and maintaining aquatic communities in rare habitats is crucial for land management and biological conservation. We investigated the relative roles of environmental and spatial factors influencing beta (β) diversity of aquatic macroinvertebrate assemblages in 36 interdunal wetlands from five freshwater sand dune areas across two ecoregions spanning the latitudinal gradient of Lake Michigan. We hypothesised that aquatic macroinvertebrate diversity and composition would vary along the coastline because of an underlying environmental gradient. We predicted high species replacement correlated with environmental (local and regional) conditions and increasing species diversity with decreasing latitude. We calculated sample completeness, obtained diversity estimates based on Hill numbers and used abundance‐based β partitioning and multivariate analysis to examine β diversity, and its replacement and nestedness components in relation to local and regional predictors. Despite a short latitudinal gradient, we detected a significant increase in species richness with decreasing latitude, underpinned by a strong temperature and precipitation gradient. Species replacement (balanced variation in abundance) was high at all spatial scales (wetland, dune area, ecoregion and coastline), and correlated with local and regional environmental variables. Community dissimilarity showed no marked increase with spatial extent, which suggests a system where local‐scale environmental filtering prevents dispersal driven homogenisation. Both local and bioclimatic factors were correlated with aquatic macroinvertebrate dissimilarity, but local factors played a larger role. This study simultaneously examined the response of alpha and β diversity to geographical and environmental variables. Our results indicate that macroinvertebrates respond to abiotic factors by tracking suitable environmental conditions among locally variable interdunal wetlands. Thus, high dispersal along the coastline conveys resiliency to a hydrologically dynamic wetland system, which allows aquatic macroinvertebrates to contribute an integral portion of sand dune biodiversity within the Laurentian Great Lakes region. The high species turnover found suggests that conservation strategies should consider coastline connectivity among dune areas to maintain freshwater biodiversity.

Indicators of fish population responses to avian predation with focus on double-crested cormorants

Double-crested cormorants (Nannopterum auritum) have been implicated as causes of fish population declines in many locations across their breeding range. Two challenges facing managers are identifying fisheries population metrics indicative of cormorant impacts and determining when this evidence becomes actionable. Building upon existing studies, we conducted a meta-analysis of eight data-rich systems across the Laurentian Great Lakes region of the United States for common fish population responses to changes in cormorant abundance. Specifically, we examined trends in mean total female length at age-3 (TL3), female mean length and age at 50 % maturity, and mean age evenness as indicated by Shannon’s Equitability Index. Annual observations for these metrics were independently regressed linearly against cormorant density by system for walleye (Sander vitreus), yellow perch (Perca flavescens), smallmouth bass (Micropterus dolomieu), and northern pike (Esox lucius) populations. TL3 was the most sensitive with 9 of the 14 datasets statistically significant (r2 range 0.29 to 0.86). Maturity metrics were moderately sensitive to trends in cormorant predation with mean total length at 50 % maturity significant in 4 out of 11 datasets (r2 range 0.27–0.41) and mean age at 50 % maturity significant in 3 out of 11 datasets (r2 range 0.12 – 0.51). Least sensitive was age evenness with the Shannon Index significant in 3 out of 12 datasets (r2 typically < 0.25). Of metrics tested, TL3 was the most reliable indicator of changes in cormorant effects despite varying system changes and management responses among locations.

Assessing future climate change impacts on groundwater recharge in Minnesota

• Minnesota recharge will decrease despite increased precipitation, due to increased ET. • Soil moisture availability can limit ET increase and consequently recharge decrease. • Changes in runoff can modulate recharge response to climate. • Less frozen ground in warmer future can reapportion spring runoff to recharge. Although the northern Laurentian Great Lakes region is projected to undergo major climate changes, it has had a paucity of future groundwater recharge studies. We used the state of Minnesota (USA) as a testbed to understand how recharge will respond to changing climate in upper mid-latitude, low-elevation temperate settings. Not only can this inform water resource management, but it can help probe difficult-to-predict sign changes in recharge in temperate zones, as well as the under-studied land-surface processes controlling them. Our study implemented the Community Land Model with ensemble outputs from five climate models under two emissions scenarios (RCP8.5 and RCP4.5) to investigate future changes in recharge for 2026–2055 relative to the baseline historical period of 1976–2005. We found that despite quite consistent projections of higher precipitation (P) and some local occurrences of increased recharge, state-average recharge will mostly decline or remain about the same due to warming-induced evapotranspiration (ET) increases. However, our simulations showed that several processes serve to buffer recharge decreases. In drier ecoregions in the west, soil moisture limitations start to constrain evapotranspiration, thus curbing reductions in recharge. These regions also include higher historical surface runoff due to its runoff-prone soils, and because much of future reductions in net atmospheric inputs (P-ET) are partitioned to lower this runoff instead of recharge, decreases in recharge are further modulated. Statewide warming also lessens frozen ground coverage, reapportioning early spring runoff of snowmelt to infiltration and recharge. Our results demonstrate that in addition to precipitation change and warming, moisture feedbacks on ET and the influence of hydrogeological properties and frozen ground dynamics on runoff must be considered when quantifying climate change impacts on recharge in temperate zones.

Extreme water level rise across the upper Laurentian Great Lakes region: Citizen science documentation 2010–2020

As the global water balance accelerates in a warming climate, extreme fluctuations in the water levels of lakes and aquifers are anticipated, with biogeochemical, ecological and water supply consequences. However, it is unclear how site-specific factors, such as location, morphometry and hydrology, will modulate these impacts on regional spatial scales. Here, we report water level time series collected by citizen scientists for 15 diverse inland lakes in the upper Laurentian Great Lakes region from 2010 to 2020, and we compare these time series with those for the two largest Great Lakes, Lake Superior and Lake Michigan-Huron. Combined with historical data (1942–2010), the findings indicate that lakes spanning seven orders of magnitude in size (10−2 to 105 km2) all rebounded from record low to record high water levels during the recent decade. They suggest coherent water level oscillations among regional lakes (large and small) implying a common, near-decadal, climatic driver that may be changing.

Utility of Shell-Valve Outlines for Distinguishing among Four Lampsiline Mussel Species (Bivalvia: Unionidae) in the Great Lakes Region

Four freshwater mussel species from the tribe Lampsilini found in the Laurentian Great Lakes region—Lampsilis fasciola (Wavy-rayed Lampmussel), Lampsilis cardium (Plain Pocketbook), Ortmanniana ligamentina (Mucket), and Lampsilis siliquoidea (Fatmucket)—have similar and variable shell morphologies that make some specimens difficult to identify in the field. Identification is further confounded by sexual dimorphism in three of the four species. We used landmark-based morphometric analyses of shell shape in conjunction with DNA barcoding to quantify shell-shape differences between the species. We collected specimens (N = 388) from Great Lakes tributaries in Michigan, USA, and Ontario, Canada. We photographed each specimen and made an initial identification in the field. We then took a tissue biopsy or swab from 248 of the specimens, sequenced a fragment of the mitochondrial cytochrome c oxidase subunit 1 (COI) gene, and confirmed identifications by comparing our sequences with sequences for all four species accessioned in GenBank. On the photographs, we digitized 21 two-dimensional landmarks along the shell margin and used multivariate methods to evaluate the correspondence of shell shape to our COI-confirmed species identifications and sex determinations. Principal-components analysis and linear-discriminant analysis of shell shape correctly identified only 77.8% of specimens to species and 72.2% to species and sex. Sex determination was particularly confounded by the similar shapes of female L. fasciola and female L. cardium specimens. This study demonstrates the limitations of using only two-dimensional valve shape in differentiating among some mussel species.

Groundwater in Crisis? Addressing Groundwater Challenges in Michigan (USA) as a Template for the Great Lakes

Groundwater historically has been a critical but understudied, underfunded, and underappreciated natural resource, although recent challenges associated with both groundwater quantity and quality have raised its profile. This is particularly true in the Laurentian Great Lakes (LGL) region, where the rich abundance of surface water results in the perception of an unlimited water supply but limited attention on groundwater resources. As a consequence, groundwater management recommendations in the LGL have been severely constrained by our lack of information. To address this information gap, a virtual summit was held in June 2021 that included invited participants from local, state, and federal government entities, universities, non-governmental organizations, and private firms in the region. Both technical (e.g., hydrologists, geologists, ecologists) and policy experts were included, and participants were assigned to an agricultural, urban, or coastal wetland breakout group in advance, based on their expertise. The overall goals of this groundwater summit were fourfold: (1) inventory the key (grand) challenges facing groundwater in Michigan; (2) identify the knowledge gaps and scientific needs, as well as policy recommendations, associated with these challenges; (3) construct a set of conceptual models that elucidate these challenges; and (4) develop a list of (tractable) next steps that can be taken to address these challenges. Absent this type of information, the sustainability of this critical resource is imperiled.

Heavy Lake-Effect Snowfall Changes and Mechanisms for the Laurentian Great Lakes Region

Heavy lake-effect snowfall (HLES) events are snowfall events enhanced by interactions between lakes and overlying cold air. Significant snowfall rates and accumulations caused during such events disrupt socioeconomic activities and sometimes lead to lethal consequences. The aim of this study is to assess projected changes to HLES by the end of the century (2079–2100) using a regional climate model for the first time with 3D representation for the Laurentian Great Lakes. When compared to observations over the 1989–2010 period, the model is able to realistically reproduce key mechanisms and characteristics of HLES events, thus increasing confidence in future projections. Projected changes to the frequency and amount of HLES suggest decreasing patterns, during the onset, active and decline phases of HLES. Despite reduced lake ice cover that will allow enhanced lake–atmosphere interactions favouring HLES, the warmer temperatures and associated increase in liquid to solid precipitation ratio along with reduced cold air outbreaks contribute to reduced HLES in the future climate. Analysis of the correlation patterns for current and future climates further supports the weaker impact of lake ice fraction on HLES in future climates. Albeit the decreases in HLES frequency and intensity and projected increases in extreme snowfall events (resulting from all mechanisms) raise concerns for impacts on the transportation, infrastructure and hydropower sectors in the region.

Elevated methylmercury concentration and trophic position of the non-native bloody red shrimp (Hemimysis anomala) increase biomagnification risk in nearshore food webs

The establishment of non-native species can result in complex shifts in food-web structure and ecosystem function that alter the bioaccumulation, transfer, and biomagnification of contaminants. Hemimysis anomala (the bloody red shrimp), a mysid native to the Ponto-Caspian region that is now established throughout the Laurentian Great Lakes region (North America) and Europe, is characterized by high densities and a trophic ecology that may be consequential to mercury fluxes and bioaccumulation. We combined methylmercury (MeHg) and stable isotope (δ15N and δ13C) analyses of invertebrates from Seneca Lake (NY, USA) to test the hypotheses that mercury concentrations differ among (1) H. anomala and native or naturalized analogs due to food-web position and (2) stages of H. anomala due to ontogenetic diet shifts. The MeHg concentration and δ15N of H. anomala exceeded other littoral invertebrates (such as amphipods, dreissenid mussels, and zooplankton >153 μm) and were as high as the pelagic, native Mysis diluviana. These taxa-specific patterns indicate intensified biomagnification of MeHg is possible in nearshore and reef-spawning fish following the establishment of H. anomala, an energy-dense prey item for economically and ecologically important fish. Larger, adult H. anomala had higher MeHg concentrations and more enriched δ15N than juveniles, and H. anomala collected at a littoral site had higher MeHg than a canal site. These intraspecies contrasts are consistent with the shift toward zooplanktivory in adult H. anomala. As both putative prey for fish and competitors for shared zooplankton resources, H. anomala may impact fish in compounding ways.

Limited Co- existence of Native Unionids and Invasive Dreissenid Mussels more than 30 Y Post Dreissenid Invasion in a Large River System

There are serious concerns for native freshwater mussel survival (Bivalvia: Unionidae) in the Laurentian Great Lakes region after populations were seemingly pushed to the brink of extirpation following the introduction of dreissenid mussels (Dreissena polymorpha and D. rostriformis bugensis) in the mid-1980s. The Detroit River was the first major river system in North America to be invaded by dreissenids, and unionids were considered extirpated from the river by 1998. Since then several unionid refuges (areas with relatively low dreissenid impact and surviving unionids) have been found in coastal areas of lakes St. Clair and Erie, but no documentation exists in the Detroit River. To assess dreissenid presence and potential unionid persistence, a mixture of stratified random, historical, and potential refuge sites were surveyed during summer 2019 in the Detroit River. Unionid and dreissenid habitat use was further investigated with analysis of variance and classification tree analyses. Of the 56 sites surveyed, only five sites had live unionids totaling 220 animals of 11 species. More than 2000 unionid shells of 31 species were collected from 39 sites, confirming the large and diverse unionid populations that existed prior to the dreissenid invasion. Ninety-eight percent of live unionids found showed evidence of past or present dreissenid attachment. Estimated dreissenid densities were highly variable with river location and ranged from 0 to 5673 live individuals per m2, with the largest densities concentrated in the upstream half of the Detroit River. Despite their previously assumed extirpation from the Detroit River, live unionids were found during this comprehensive survey. Although only 40% of the historical species within the unionid assemblage remains, our results suggest, in the right conditions, some coexistence is possible among some species of unionids and dreissenids in this large river system.

Can otolith microchemistry identify the natal origin of larval lake whitefish Coregonus clupeaformis in the waters of Green Bay?

Lake whitefish Coregonus clupeaformis play a key role in the socioeconomics of the Laurentian Great Lakes region and serve as an important conduit of energy among trophic levels. Lake wide declines in adult abundance creates the need for improved understanding of population dynamics, currently hampered by a lack of early life history information and resolution of subpopulation structure. We predicted that otolith microchemistry had the potential to broaden our understanding of lake whitefish ecology by determining the natal origin of larvae at a resolution (e.g., spawning location) unachievable with other techniques. To test this prediction, in 2017 and 2018, recently hatched, pelagically-drifting lake whitefish larvae were collected from the open waters of Green Bay, Lake Michigan and four large tributaries (Menominee, Fox, Oconto and Peshtigo Rivers), where spawning activity has been recently documented. Linear discriminant function analyses conducted at the broadest level of resolution (i.e., river vs. open-water origin) correctly assigned 80.5% and 75.0% of individuals to their natal location in 2017 and 2018, respectively. Reclassification success at a finer resolution (i.e., specific rivers) ranged from 75.9% in 2017 to 42.1% in 2018. We discuss these promising results with respect to underlying variation in geological features, water chemistry and interannual river conditions that eggs and larvae experience during incubation and before prolonged drift.

A 900-year record of effective moisture in the Laurentian Great Lakes region

The (Laurentian) Great Lakes region (GLR) of North America contains ∼20% of the world's freshwater by total area. Yet, the water quantity and quality of lakes in this region are threatened by water level fluctuations and excessive algal growth associated with climate warming. To understand the mechanisms that drive these changes, we have established a 900-year history of environmental change using sediments from a small kettle lake, Barry Lake, located within the GLR. To understand how water quantity changed over time, we used stable isotopes of oxygen and carbon in marl to reconstruct effective moisture. Our reconstruction for Barry Lake shows that the Little Ice Age (LIA) was wetter than present, whereas the Medieval Climate Anomaly (MCA) was drier than present. There is considerable spatiotemporal variation in effective moisture across the GLR and northeastern (NE) USA. This variation may reflect changes in the sign of the Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO), which can alter moisture delivery by modifying the strength and position of the polar and subtropical jet streams. To identify changes in water quality, we reconstructed primary production using sedimentary chlorophyll a (Chl-a(s)) contents and stable isotopes of carbon and nitrogen in organic matter. There was relatively little change until the last 150 years, revealing that shifts in effective moisture did not noticeably influence primary production. Rather, primary production was impacted by anthropogenic pressures such as land use change and associated increases in nutrient delivery. Our research contextualizes recent threats to water quantity and quality in the GLR against a backdrop of environmental change, while also synthesizing hydroclimate records from across this region and the NE USA.

Building the Digital Extended Specimen: A case study of invasive European frog-bit (Hydrocharis morsus-ranae L.)

The Extended Specimen was first described by Webster (2017). He defined a “constellation of specimen preparations and data types,” centered around an occurrence of an organism, which captures the breadth of empirical facts about an organism’s phenotype, genotype, and ecology in space and time. The Extended Specimen Network was embraced by the collections community in the Biodiversity Collections Network Extended Specimen Report (Lendemer et al. 2020) and the National Academies of Science, Engineering, and Medicine Future of Collections report (Lendemer et al. 2020, National Academies of Science, Engineering, and Medicine 2020). Several global discussions are underway to build a common definition of the Digital Extended Specimen (DES) and elucidate next steps in building the infrastructure to support Digital Extended Specimens and their network of associated data (including efforts among Distributed System of Scientific Collections (DiSSCo), Biodiversity Collections Network (BCoN), GBIF’s Alliance for Biodiversity Knowledge, TDWG's Task Group on Minimum Information about a Digital Specimen (MIDS), and others.) At the foundation of the DES is the occurrence of an organism in time and space, which is represented by physical specimens or observations serving as tokens of reality. Tokens are translated to digital records, which can be extended through a network of linkages between them and with derived and associated data, e.g. project methodologies, environmental conditions, habitat characteristics, and associated taxa. For digital records to be integrated with the larger network of Digital Extended Specimens, they must become FAIR digital objects that are Findable, Accessible, Interoperable, and Reusable (Wilkinson et al. 2016). By translating the Digital Extended Specimen concept to the local project scale, we provide opportunities to move beyond a theoretical understanding of the DES and towards a practical framework for its implementation. Here we present and discuss the power, limits, and questions in the implementation of the Digital Extended Specimen framework by applying it to the case study of an invasive aquatic plant in the Laurentian Great Lakes region. European frog-bit (Hydrocharis morsus-ranae L.; EFB) is native to western and northern Eurasia and invasive in North America and India. Dense mats of EFB may hinder commercial and recreational use of waterways and decrease light, dissolved oxygen, and native species diversity. We describe a multi-taxonomic study that examined EFB along with associated plant species, animal species, and environmental characteristics (Monfils et al. 2021). The integration of such diverse types of empirical data is a necessary prerequisite for determining the factors associated with EFB establishment, the impacts of EFB on native coastal wetland ecosystems, and the development of suitable management regimes for the conservation of native biodiversity. Data gathered from this study are housed in a local database. In our database, we consider both physical specimens and recorded observations as tokens of concrete occurrences of EFB, which define the base units. These tokens are linked to their collection events, which provide environmental and sampling context, as well as co-occurrences of other taxa including plants, invertebrates, fish, anurans, reptiles, and birds. Digitally linked, these extensions of each digital representation of a collected token provide not only empirical evidence of an EFB occurrence, but also directly connect it with all additionally sampled, derived, and associated information. Through this network of extensions we gain a more holistic understanding of EFB’s species associations, habitats, and ecosystem impacts at the level of populations and communities. The application of the Digital Extended Specimen framework at the project level illustrates how the DES can be used in a real-world context and highlights challenges in translating the concept from a theoretical to a practical perspective.

Analysis of the Atmospheric Water Cycle for the Laurentian Great Lakes Region Using CMIP6 Models

AbstractThis study evaluates the historical climatology and future changes of the atmospheric water cycle for the Laurentian Great Lakes region using 15 models from phase 6 of the Coupled Model Intercomparison Project (CMIP6). While the models have unique seasonal characteristics in the historical (1981–2010) simulations, common patterns emerge in the midcentury SSP2–4.5 scenario (2041–70), including a prevalent shift in the precipitation seasonal cycle with summer drying and wetter winter and spring months, and a ubiquitous increase in the magnitudes of convective precipitation, evapotranspiration, and moisture inflow into the region. The seasonal cycle of moisture flux convergence is amplified (i.e., the magnitude of winter convergence and summer divergence increases), which is the primary driver of future total precipitation changes. The precipitation recycling ratio is also projected to decline in summer and increase in winter by midcentury, signifying a larger contribution of the regional moisture (via evapotranspiration) to total precipitation in the colder months. Most models (10/15) either do not represent the Great Lakes or have major inconsistencies in how the lakes are simulated both in terms of spatial representation and treatment of lake processes. In models with some lake presence, the contribution of lake grid cells to the regional evapotranspiration magnitude can be more than 50% in winter. In the future, winter months have a larger increase in evaporation over water surfaces than the surrounding land, which corroborates past findings of sensitivity of deep lakes to climate warming and highlights the importance of lake representation in these models for reliable regional hydroclimatic assessments.

Using Uncrewed Aerial Vehicles for Identifying the Extent of Invasive Phragmites australis in Treatment Areas Enrolled in an Adaptive Management Program

Higher spatial and temporal resolutions of remote sensing data are likely to be useful for ecological monitoring efforts. There are many different treatment approaches for the introduced European genotype of Phragmites australis, and adaptive management principles are being integrated in at least some long-term monitoring efforts. In this paper, we investigated how natural color and a smaller set of near-infrared (NIR) images collected with low-cost uncrewed aerial vehicles (UAVs) could help quantify the aboveground effects of management efforts at 20 sites enrolled in the Phragmites Adaptive Management Framework (PAMF) spanning the coastal Laurentian Great Lakes region. We used object-based image analysis and field ground truth data to classify the Phragmites and other cover types present at each of the sites and calculate the percent cover of Phragmites, including whether it was alive or dead, in the UAV images. The mean overall accuracy for our analysis with natural color data was 91.7% using four standardized classes (Live Phragmites, Dead Phragmites, Other Vegetation, Other Non-vegetation). The Live Phragmites class had a mean user’s accuracy of 90.3% and a mean producer’s accuracy of 90.1%, and the Dead Phragmites class had a mean user’s accuracy of 76.5% and a mean producer’s accuracy of 85.2% (not all classes existed at all sites). These results show that UAV-based imaging and object-based classification can be a useful tool to measure the extent of dead and live Phragmites at a series of sites undergoing management. Overall, these results indicate that UAV sensing appears to be a useful tool for identifying the extent of Phragmites at management sites.