Detection Of Invasive Species Research Articles

Evaluation of eDNA qPCR monitoring as an early detection tool for a non-native mysid in Great Lakes Waters

Early detection of aquatic invasive species (AIS) is vital to cost-effective prevention of their spread in the Great Lakes. Unfortunately, AIS surveillance has been generally too slow and geographically limited to support this purpose. Environmental DNA (eDNA) detection using quantitative polymerase chain reaction (qPCR) offers more rapid and affordable detection of likely AIS presence, but it does not directly discern live/dead status. Vital status verification using conventional surveys following positive eDNA qPCR detections could resolve this barrier, but only if the latter are adequately reliable and sensitive. Here we explore the reliability and sensitivity of eDNA qPCR monitoring for the bloody red shrimp (Hemimysis anomala), an AIS established in the southern Great Lakes but not yet widely distributed in Lake Superior, against conventional microscopy-based methods. We conducted this comparison using 1) harbor water from Muskegon Lake, MI where H. anomala is established, and 2) raw ballast water from ships transporting ballast from lower Lake Michigan to western Lake Superior. Our studies showed positive eDNA qPCR detections of H. anomala in all harbor and ballast samples for which conventional detection results were positive, and in some samples for which conventional results were negative. These results suggest that qPCR assays with adequate specificity could be an important tool in support of more effective and affordable early detection of target species in Great Lakes water, especially when combined with confirmatory conventional monitoring.

The third invasive Anoplophora: Citizen science facilitates uncovering massive abundance of non-native A. horsfieldii (Coleoptera: Cerambycidae) in South Korea

The longhorned beetle genus Anoplophora contains highly destructive species in the field of invasive entomology. Recently, the establishment of the non-native member of the genus, Anoplophora horsfieldii (Hope, 1843), has been documented in South Korea. However, the degree of impact of A. horsfieldii in invaded area remains uncertain due to the limited number of individuals surveyed, making it harder to classify them as invasive. This study combines data from both citizen scientists and naturalists to investigate the occurrence status and distribution range of A. horsfieldii. In total, 1,156 individuals were collected, with 1,124 of them collected in 2023 alone. Citizen-contributed data accounted for 52.5%, enabling us to estimate the preliminary occurrence period and population peak. This research identifies A. horsfieldii as the third invasive species within the genus Anoplophora and underscores the importance of citizen science in early detection and ecological surveys of invasive species.

Is it there?—Estimating the invasion of armored sailfin catfish (Pterygoplichthys sp.) in the water bodies of Eastern Ghats, India using the eDNA approach

AbstractEarly detection of invasive species is crucial for effectively controlling the potential damage they can inflict on the ecosystems. In contrast to the many limitations that conventional detection methods like visual surveys and netting hold, environmental DNA assay provides a powerful alternative. This non‐invasive, highly sensitive, and user‐friendly technique offers the advantage of detecting invasive species even in areas where direct observation is challenging, thus addressing the shortcomings of traditional techniques and enhancing overall accuracy in estimating distribution. The spread of invasive Pterygoplichthys sp. has become a cause for concern in biodiversity‐rich countries like India. Despite this, comprehensive studies on the prevalence of this invasive species are limited. The Eastern Ghats of India remain under‐explored with a high potential for supporting diverse lifeforms. Studying the extent of biological invasions in the Eastern Ghats is essential for effective management and to mitigate the ecological and socioeconomic impacts of invasive species. In this study, we have designed and optimized an eDNA‐based quantitative PCR assay to map the presence and spread of invasive Pterygoplichthys sp. in selected freshwater ecosystems of the Eastern Ghats. This assay detected invasive Pterygoplichthys sp. in almost 65% of the total locations sampled. This study can be further extended to larger geographical areas, which can contribute to formulating necessary measures by the authorities to manage invasion and conserve the diversity of the freshwater ecosystem.

New dockside eDNA based protocol to detect the seaweed Asparagopsis armata evaluated by stakeholders

Early detection of invasive species is crucial to deal effectively with biological invasions in ports, which are hotspots of species introductions. In this study, a simplified end-time PCR methodology conducted on eDNA from water samples was developed for rapid detection of the invasive seaweed Asparagopsis armata (four hours from water collection to result visualization). It was tested dockside in four international Spanish ports in presence of stakeholders, whose feedback was obtained to explore the real applicability of this biotechnology. Although biological invasions were not a main concern for them, results indicate a unanimous approval of the methodology by the stakeholders, having detected the presence of A. armata in three of the ports. Stakeholders suggested further developments for easier application of the tool and multiple species detection, to be adopted for the control of invasive species in ports.

Advanced Detection of Invasive Neophytes in Agricultural Landscapes: A Multisensory and Multiscale Remote Sensing Approach

The sustainable provision of ecological products and services, both natural and man-made, faces a substantial threat emanating from invasive plant species (IPS), which inflict considerable economic and ecological harm on a global scale. They are widely recognized as one of the primary drivers of global biodiversity decline and have become the focal point of an increasing number of studies. The integration of remote sensing (RS) and geographic information systems (GIS) plays a pivotal role in their detection and classification across a diverse range of research endeavors, emphasizing the critical significance of accounting for the phenological stages of the targeted species when endeavoring to accurately delineate their distribution and occurrences. This study is centered on this fundamental premise, as it endeavors to amass terrestrial data encompassing the phenological stages and spectral attributes of the specified IPS, with the overarching objective of ascertaining the most opportune time frames for their detection. Moreover, it involves the development and validation of a detection and classification algorithm, harnessing a diverse array of RS datasets, including satellite and unmanned aerial vehicle (UAV) imagery spanning the spectrum from RGB to multispectral and near-infrared (NIR). Taken together, our investigation underscores the advantages of employing an array of RS datasets in conjunction with the phenological stages, offering an economically efficient and adaptable solution for the detection and monitoring of invasive plant species. Such insights hold the potential to inform both present and future policymaking pertaining to the management of invasive species in agricultural and natural ecosystems.

First inventory of Ants (Hymenoptera: Formicidae) with detection of potential invasive species in National Park of Ehotilés islands, Côte d’Ivoire

Estuarine and wetland ecosystems are becoming increasingly altered by the concentration of human population near the coastline. A major threat to biodiversity related to this human footprint is the introduction of invasive alien species, particularly in isolated ecosystems like islands where biological invasion is often harmful. The National Park of Ehotilés Islands is an archipelago of 6 islands and a RAMSAR site subjected to disturbances activities like agriculture, illegal fisheries, and tourism. These factors often act as an accelerator for the introduction of invasive species. However, there is a lack of research conducted on insects, specifically ants on these islands. This study aimed to inventory the present ant fauna and estimate the vulnerability to tramp and potential invasive ant species. Ants were collected using Winkler, pitfall, and funnel traps on five islands. In total, 76 ant species were recorded. These species are distributed into 20 genera and five subfamilies: Dolichoderinae (5 species), Formicinae (11 species), Myrmicinae (49 species), Ponerinae (11 species) and Proceratiinae (1 species). We also detected two tramp and potentially invasive species: the ghost ant Tapinoma melanocephalum and the big-headed ant Pheidole megacephala. Ant communities are dominated by six species, namely Odontomachus troglodytes, Oecophylla longinoda, Nylanderia lepida, Pheidole sp.2, Monomorium invidium, and the invasive ghost ant Tapinoma melanocephalum. This work is the first to inventory ants on the Islands of Ehotilés National Park and may serve as a basis for conservation decisions as it demonstrates that this park is not spared from the introduction of invasive ant species.

Potential invasive species detection of Demospongiae using environmental DNA in Sabang and Lhokseumawe Ports

Sabang and Lhokseumawe Ports are located in the province of Aceh and constitute part of the northern Malacca Strait, sharing direct borders with neighboring countries such as Malaysia, Thailand, and India. Strategic geographical location significantly influences the oceanographic conditions and biodiversity of the area. As marine organisms, sponges play a crucial role in the ecosystem, yet research on their identification in the Sabang and Lhokseumawe regions is limited. The analysis of community structure and identification of species can be conducted using various approaches, including environmental DNA (e-DNA) analysis. This study aimed to assess water quality and identify the presence of potentially invasive Demospongiae using DNA Metabarcoding in Sabang and Lhokseumawe Ports. The measurement results of the water conditions indicate that the waters around Sabang and Lhokseumawe ports generally exhibit values that support sponge life. e-DNA analysis successfully detected the presence of the Demospongiae class, with 260 Operational Taxonomic Units (OTUs) in Sabang waters and 148 OTUs in Lhokseumawe waters. One commonly found genus, Cliona sp., has the potential to become invasive in both locations, posing a risk of bioerosion to corals under specific conditions.

Distribution of the Cannabis sativa L. in the Western Himalayas: A tale of the ecological factors behind its continuous invasiveness

The invasion of species in new regions depends on multiple factors, especially, the prevailing environmental factors. The environmental conditions are essential to understand for planning effective management strategies related to invasive species. Little is known about Cannabis as an established invasive weed. We hypothesized that the successful establishment of this invading species is influenced by the environmental variables; however, some of them have a much stronger influence than the others. Quantitative ecological methods were adopted for sampling the habitats invaded by Cannabis sativa, in a total of 165 quadrats. Soil samples were collected for soil analyses from each of those quadrat. Ecological and statistical approaches including Structure Equation Modeling (SEM) procedures were applied to evaluate the impact of environmental factors, ecological interrelationships, and the resultant invasiveness of the C. sativa. Our findings indicate that elevation, temperature, humidity, anthropogenic pressure, physio-chemical prperties of soil and habitat degradation play significant roles in determining the distribution and abundance of C. sativa. Principal Component Analysis (PCA) of the parameters further clarifies that elevation is the most important driver in explaining the successful establishment of the invader species with a 30.1% variance. Structural equation modeling further confirms the significant role played by elevation, which not only directly affects the abundance of Cannabis but also indirectly influences other variables such as anthropogenic pressure, temperature, and humidity etc. However, the invasion of C. sativa is less affected by soil saturation pH, electrical conductivity, phosphorous, potassium, and CaCO3. Our study provides valuable scientific information that could be used for the early detection of invasive species at the early stage of invasion and in devising policies for their management and control.

Dealing with imperfect data for invasive species detection using multispectral imagery

Detection and monitoring invasive species can provide valuable ecological information to guide management decisions. Multispectral imagery remote sensing may be an ideal tool to address this problem by providing accurate and affordable repeat imagery. However, developing training datasets for remote sensing imagery can be riddled with issues such as matching a training site to a single pixel in target imagery or mixed pixels caused by low invader densities. The multitarget multiple-instance spectral match filter (MTMI-SMF) algorithm accounts for such errors and has low computation costs. Here, we evaluated MTMI-SMF for invasive species detection with National Agriculture Imagery Program (NAIP), RapidEye, and Landsat imagery using Brazilian peppertree (Schinus terebinthifolia) in the Everglades National Park as a case study. MTMI-SMF detected Brazilian peppertree with an area under the curve (AUC) of 0.85 for Landsat, 0.82 for RapidEye, and 0.71 NAIP imagery. Invader classification was developed using a threshold calculated from MTMI-SMF image detection confidence values and compared to a random forest classification. MTMI-SMF and random forest classifications had similar overall accuracies with NAIP imagery performing the lowest (an average of 73.6% and 88.9%, respectively) and Landsat performing the highest (an average of 90.9% and 91.4%, respectively). However, due to the relatively rare nature of Brazilian peppertree across this landscape, the overall classification accuracy was not fully representative of detection capabilities. MTMI-SMF outperformed random forest for user accuracy and had comparable producer accuarcy across all three image sources. Classifications primarily relied on the brighter signature of Brazilian peppertree due to the limited number of spectral bands in the multispectral imagery. As a result, confusion was caused by heterogeneous vegetation communities or shrub habitats, which most likely could be resolved with the increased availability of satellite hyperspectral datasets. Our study indicates that MTMI-SMF, a machine-learning approach that allows flexibility in training data, can detect highly problematic invaders using multispectral imagery. This pipeline could be readily adapted to other invaders and ecosystems, as well as different remote sensing image sources, and has low computational requirements. Our study demonstrates that remote sensing technologies and multiple-instance learning algorithms can provide managers with critical tools for tackling the ever-growing, costly, and challenging problem of tracking invasive species' plant spread.

Deep learning-based image classification of turtles imported into Korea

Although turtles play a key role in maintaining healthy and balanced environments, these are endangered due to global trade to meet the high demand for food, medicine, and pets in Asia. In addition, imported non-native turtles have been controlled as alien invasive species in various countries, including Korea. Therefore, a rapid and accurate classification of imported turtles is needed to conserve and detect those in native ecosystems. In this study, eight Single Shot MultiBox Detector (SSD) models using different backbone networks were used to classify 36 imported turtles in Korea. The images of these species were collected from Google and were identified using morphological features. Then, these were divided into 70% for training, 15% for validation, and 15% for test sets. In addition, data augmentation was applied to the training set to prevent overfitting. Among the eight models, the Resnet18 model showed the highest mean Average Precision (mAP) at 88.1% and the fastest inference time at 0.024 s. The average correct classification rate of 36 turtles in this model was 82.8%. The results of this study could help in management of the turtle trade, specifically in improving detection of alien invasive species in the wild.

Incursion Preparedness, Citizen Science and Early Detection of Invasive Insects: The Case of Aleurocanthus spiniferus (Hemiptera, Aleyrodidae) in France.

We describe the process by which the quarantine whitefly, Aleurocanthus spiniferus (Hemiptera, Aleyrodidae), was detected in France. The initial observation was made by a volunteer who reported a picture of an adult in the Inventaire National du Patrimoine Naturel (INPN Espèces), a citizen science resource developed by l'Office Français de la Biodiversité and the French Muséum National d'Histoire Naturelle. The specimen was suspected to be A. spiniferus from this picture by one of the expert entomologists in charge of the Hemiptera group validation. Once the species was identified, it was mounted on a slide and the information was officially passed on to the ministry in charge of agriculture via a communication channel set up in advance for this type of situation. The ministry then triggered the regulatory actions planned in the event of the suspected detection of quarantine organisms. Sampling was quickly carried out and the specimens collected on this occasion were formally identified as belonging to the species A. spiniferus. This led to the formalization of an outbreak in France. This sequence of decisions took just two months from the first observation to the implementation of a management plan. This case presents how incursion preparedness contributes to a rapid response. Furthermore, this case exemplifies how citizen science can contribute to the early detection of invasive species and highlights the importance of informing both the general public and professionals about major environmental issues.

Research and prospects of environmental DNA (eDNA) for detection of invasive aquatic species in East Asia

Research and prospects of environmental DNA (eDNA) for detection of invasive aquatic species in East Asia

Predicting the spatio-temporal pattern of range expansion under lack of equilibrium with climate

Early detection of invasive species in regions under threat is key for biodiversity conservation. Here we conduct a retrospective study to assess whether correlative Species Distribution Models (SDMs) can predict the spatio-temporal range of expansion in an invasive species, the Asian hornet. Given that modelling invasive species distributions defies one of the main assumptions of SDMs, the equilibrium with climate, we also introduce a quantitative assessment of climatic disequilibrium in the invaded area based on hypervolume comparison between the native and invaded areas (both unoccupied and occupied territories). We evaluate the ability of three different modelling approaches (presence-only, presence-background and presence-absence) calibrated with data until 2013 to predict the species distribution observed the following years (2015, 2017, 2019, and 2021). Our results show that presence-only models based on the BIOCLIM algorithm can effectively predict the spatio-temporal pattern of invasion when predictions are rescaled based on percentiles (i.e. ranked suitability) and the model is calibrated with data from both native and invaded areas. These models predicted higher suitability values for sites that were invaded earlier in time and, importantly, they did not predict low suitability values for sites that were eventually occupied years later. Thus, they can be very useful for decision-makers and managers, as they provide a probabilistic prediction of both (i) the temporal dimension of species range expansion, and (ii) the potential distribution range in the long term. Such information would allow prioritizing monitoring efforts in the short term without losing sight of the potential risks in the long term.

The use of semiochemicals for attracting and repelling invasive ambrosia beetles (Coleoptera: Curculionidae) in ʻōhiʻa (Metrosideros polymorpha) forests

Abstract Early detection of invasive species is critical for preventing ecological and economic damage and maintaining ecosystem health. In Hawaiʻi, a complex of generalist ambrosia beetle species in the tribe Xyleborini (Coleoptera: Scolytinae) are threatening the health and productivity of forests and crops due to their association with tree diseases such as rapid ʻōhiʻa death (ROD) and key agricultural commodities including coffee and macadamia. We conducted trapping experiments to determine the efficacy of semiochemicals to attract and repel Xyleborini ambrosia beetles within two ʻōhiʻa (Metrosideros polymorpha) forests on the Island of Hawaiʻi. We compared the attraction of beetles to 100% ethanol and a 1:1 mixture of ethanol: methanol at Waiākea Forest Reserve and ʻŌlaʻa Forest in Hawaiʻi Volcanoes National Park. In addition, we tested the extent to which verbenone and verbenone + methyl salicylate repellents (SPLAT® Verb and SPLAT® Beetle Guard, respectively) deterred beetles from baited traps at Waiākea Forest Reserve in two separate experiments. For all invasive ambrosia beetle species, including Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xyleborus perforans, Xylosandrus compactus, and Xylosandrus crassiusculus, more beetles were captured in traps baited with 100% ethanol than 1:1 ethanol: methanol. Across all species, both repellents were effective, with fewer beetles captured in traps equipped with repellents. Our research demonstrates the utility of semiochemicals for attracting and repelling invasive ambrosia beetle species in Hawaiʻi, and the potential use of these tools for early detection and management strategies.

Diversity of insect pests of common bean and pigeon pea in the Republic of Congo revealed by DNA barcoding

In Central Africa, the development of leguminous crops is accompanied by a proliferation of pests, such as seed-beetles (Coleoptera: Chrysomelidae: Bruchinae). Integrated biological control against insect pests requires a preliminary phase of early detection and monitoring of potential invasive species, which is often limited by the availability of diagnostic morphological characteristics. DNA barcoding represents a powerful molecular tool for identifying specimens, and the mitochondrial sequences produced can provide information concerning the origins of introduced species. In this study, we characterized the diversity of insect pests present in farmer storage sites and plots of common bean and pigeon pea, by using DNA barcoding of specimens sampled in the five main agricultural regions of the Republic of Congo. The cosmopolitan seed-beetle species Acanthoscelides obtectus (Say, 1831) (Coleoptera: Chrysomelidae: Bruchinae) was recognized as the major pest sampled on common bean. The sub-Saharan species Specularius erythraeus (Pic, 1908) (Coleoptera: Chrysomelidae: Bruchinae) was the main species found in pigeon pea plots, sometimes co-occurring with the cosmopolitan species Callosobruchus maculatus (Fabricius, 1775) (Coleoptera: Chrysomelidae: Bruchinae). A fourth bruchine, Zabrotes subfasciatus (Boheman, 1833), and two moth species were also recognized: a species of the genus Mussidia Ragonot, 1888 (Pyralidae) and the cosmopolitan pest of stored food, Cadra cautella (Walker, 1863) (Pyralidae). These results differ from species lists compiled in the 1980s, thus providing updated knowledge concerning the pest species present in this region and fundamental information for choosing appropriate methods of control.

Automated lab-on-chip for the specific detection of invasive species through environmental DNA

The ability to detect nucleic acid sequences is revolutionizing the fast identification of specific organisms, particularly with Lab-on-a-chip systems. However, these often rely on complex processes, skilled personnel, and external control devices which limits automation. To address this, we present an automated, portable, and easy-to-fabricate lab-on-chip that combines enzyme-assisted DNA signal amplification and optical detection for in-situ monitoring of zebra mussel invasive species in the environment. Zebra mussels DNA triggers enzyme-assisted signal amplification through hybridization, leading to a quantitative colorimetric response. The sensing performance exhibited enhanced sensitivity when increasing AuNPs diameter from 23.3 ± 1.6 to 67.4 ± 2.0 nm. Quantitative colorimetric approaches displayed an LoD of 0.5 pM, 19-fold increase in sensitivity when compared to naked eye. The system enabled to discriminate single nucleotide polymorphism (SNP) for concentrations from 130 pM and to successfully analyse Zebra mussel samples from the Guadalquivir River. Experiments were conducted by the user and an automated device. The accuracy was tested with a 60 pM sample which was pre-treated externally and analysed by the automated system resulting in relative error of 16.8% and 13.4%, respectively. The automated system reduced the analysis time by 1 h and 20 min, great advantage for in-situ analysis.

Environmental suitability and detection of cnidarian invasive species at Dumai and Kuala Tanjung Port using eDNA

The Malacca Strait is Indonesia’s most strategic traffic lane to support ship logistics activities. Ships with ballast water transfer systems can raise water quality issues, distribute foreign microorganisms, or introduce invasive species globally. Phylum Cnidaria has a strong potential to invade waters because all species in this phylum have nematocysts that function to penetrate toxins. This study aimed to determine oceanographic conditions and identify invasive species in the phylum Cnidaria based on eDNA approaches in the waters of the Rupat Strait and Kuala Tanjung Port. Sample identification found 114 species of Cnidaria at Dumai Port and 112 species at Kuala Tanjung Port. Fertility waters were detected to have mesotrophic status at Dumai Port and Eutrophic at Kuala Tanjung Port. Based on the Global invasive species database, we found Ectopleura crocea and Pelagia noctiluca, native to the Mediterranean Sea and North Atlantic Ocean. Environment parameter conditions support the existence of invasive species in both study sites.

Identification and characterization of Entyloma eschscholziae, a recently introduced pathogen in Europe, and its segregate Entyloma dendromeconis sp. nov.

AbstractEntyloma includes pathogenic and saprobic species that infect or colonize dicotyledonous host plants. Although most Entyloma species are known only from native areas of occurrence, some species were introduced with their host plants and spread outside their natural areas. The identification of introduced species is important for detection and management of invasive species. In this study, the morphology, phylogeny and species boundaries of Entyloma eschscholziae, recently introduced from North America to Europe, are revisited. Morphology was similar among the type and other specimens of E. eschscholziae analysed on Eschscholzia californica. Both asexual and sexual morphs were observed. The rDNA ITS1‐5.8S‐ITS2 sequences of the E. eschscholziae specimens from Europe and New Zealand and the environmental sequence obtained from grassland soil in California, United States, were identical. Morphological and molecular analyses confirm that the causative agents of white smut on E. californica in native (North America) and introduced (Europe, New Zealand) areas belong to the same species. DNA barcodes obtained in this study (especially ITS sequence from the designated epitype specimen) could be used to facilitate its molecular identification. Specimens on Dendromecon rigida, previously assigned to E. eschscholziae, are morphologically distinct. An attempt to obtain DNA barcode data from degraded holotype material was not successful and no more recent material is available. However, based on the morphological differences and high host specificity found in Entyloma spp., it is appropriate to describe a new species, Entyloma dendromeconis, for this smut pathogen.

First record of Leptoglossusoccidentalis Heidemann, 1910 (Hemiptera, Coreidae) in the Canary Islands, a novel pine pest detected through citizen science in an oceanic archipelago.

The 'western seed bug', known as Leptoglossusoccidentalis, is considered a global invasive species that has experienced a recent rapid expansion worldwide, becoming an important pest species for coniferous forests. With the 'Canary Islands early-warning network for the detection and intervention of invasive exotic species' (RedEXOS), this species was detected for the first time in the Canarian archipelago in an urban area in the eastern part of the island of Gran Canaria. This early detection is crucial for understanding the potential damage in one of the islands with the highest surface area of natural endemic pine forest.

Environmental DNA (eDNA) removal rates in streams differ by particle size under varying substrate and light conditions

The use of environmental DNA (eDNA) as a sampling tool offers insights into the detection of invasive and/or rare aquatic species and enables biodiversity assessment without traditional sampling approaches, which are often labor-intensive. However, our understanding of the environmental factors that impact eDNA removal (i.e., how rapidly eDNA is removed from the water column by the combination of decay and physical removal) in flowing waters is limited. This limitation constrains predictions about the location and density of target organisms after positive detection. To address this question, we spiked Common Carp (Cyprinus carpio) eDNA into recirculating mesocosms (n = 24) under varying light (shaded versus open) and benthic substrate conditions (no substrate, bare substrate, and biofilm-colonized substrate). We then collected water samples from each mesocosm at four time points (40 min, 6 h, 18 h, and 48 h), and sequentially filtered the samples through 10, 1.0, and 0.2 μm filters to quantify removal rates for different eDNA particle sizes under varying light and substrate conditions. Combining all size classes, total eDNA removal rates were higher for mesocosms with biofilm-colonized substrate compared to those with no substrate or bare (i.e., no biofilm) substrate, which is consistent with previous findings linking biofilm colonization with increased eDNA removal and degradation. Additionally, when biofilm was present, light availability increased eDNA removal; eDNA levels fell below detection after 6–18 h for open mesocosms versus 18–48 h for shaded mesocosms. Among size classes, larger particles (>10 μm) were removed faster than small particles (1.0–0.2 μm). These results suggest that changes in the distribution of eDNA size classes over time (e.g., with downstream transport) and with differing environmental conditions could be used to predict the location of target organisms in flowing waters, which will advance the use of eDNA as a tool for species monitoring and management.