Kronenberger and colleagues 2025

Kronenberger JA, Wilcox TM, Schwartz MK. 2025. SmartScreen-AIS: A high-throughput qPCR chip for nationwide surveillance of aquatic invasive species. Environmental DNA 7(3): e70144. https://onlinelibrary.wiley.com/doi/abs/10.1002/edn3.70144

Abstract

 

Effective wildlife conservation requires frequent and widespread data on species occurrence. With the maturation of eDNA-based monitoring—now widely recognized as sensitive, cost effective, and legally defensible—nationally coordinated eDNA strategies are beginning to take shape. Such ambitious initiatives will require eDNA analytics with the throughput and sensitivity required for surveillance of many protected, pathogenic, and invasive species across broad geographic scales. Here, we help meet this need with SmartScreen-AIS: a high-throughput qPCR (HT-qPCR) chip with 46 assays targeting aquatic invasive species of widespread concern. SmartScreen-AIS was validated for use throughout the continental United States and can be subdivided into smaller chip formats as desired for use in specific regions or biomes. Assay performance in HT-qPCR was strong relative to conventional qPCR, with slightly lower specificity in some cases (due to pre-amplification) but significantly higher sensitivity. Contamination was rare, PCR inhibition was minimal to nonexistent, and demonstration at three military installations detected eDNA from all species on the chip that were known to be present and one species that was previously undocumented. Cost savings will depend on the number of assays used and samples tested, but in this study we estimate that eDNA analyses were 75% cheaper using HT-qPCR than they would be with our conventional qPCR protocol. To facilitate use, we provide appendices with assay details, bench protocols, a script for processing results, and an online app with state-level assay specificity information. SmartScreen-AIS has the potential to advance early detection of invasive species in the United States, and we hope our HT-qPCR workflow inspires chip development and use globally.

 

Keywords: None provided.

 

Keywords: 

Teesalu and colleages 2025

Teesalu P, Muuga JM, Hurt M, Kaldre K, Nõges T, Ercoli F. 2025. Effects of temperature on marbled crayfish (Procambarus virginalis, Lyko 2017) invasion ecology. Hydrobiologia: 852: 3541–3558. https://doi.org/10.1007/s10750-025-05828-y

Abstract

 

The marbled crayfish (Procambarus virginalis) is an invasive freshwater species spreading across Europe. Understanding its establishment and distribution is crucial, particularly in relation to temperature. This study examined the role of water temperature in marbled crayfish invasion in a warm outflow channel of a power plant in Estonia. We hypothesized that warmer water temperatures and the temperature gradient along the channel would influence crayfish establishment, distribution, and trophic niche. Temperature loggers revealed a distinct gradient, with the channel being warmer than the adjacent reservoir, providing a more suitable habitat for crayfish. Stable isotope analysis (¹³C and ¹⁵N) with MixSIAR and SIBER models showed distinct trophic niches along the channel: crayfish at the head of the channel consumed macroinvertebrates and macrophytes, while those at the mouth mainly consumed macroinvertebrates and periphyton. Additionally, crayfish shifted from eating primary consumers in spring and summer to primary producers in autumn. Water temperature was a key factor in crayfish establishment, but food availability also likely influenced their distribution. This study highlights the role of water temperature and ecological factors in the invasion dynamics of marbled crayfish, especially in the context of global warming.

 

Keywords: Stable isotopes • trophic niche • invasive species • population dynamic • temperature effect

Buřič and colleagues 2025

Buřič M, Ložek F, Görner T, Čuprová V, Kožený P, Mojžišová M, Vlach P, Štruncová E, Petrusek A, Kouba A, Svobodová J. 2025. Difficult to deal with: attempts for eradication of marbled crayfish from a small urban pond. Management of Biological Invasions 16(2): 443–464. https://doi.org/10.3391/mbi.2025.16.2.08

Abstract

The marbled crayfish is an emerging invasive species, mainly due to parthenogenetic reproduction and high adaptability. Its successful eradication seems to be possible only in early detected populations and under favourable conditions. The population of marbled crayfish was discovered in a small urban pond in Prague, Czech Republic, in August 2020. Shortly afterwards, management was initiated with the aim of complete eradication. The pond was harvested and drained twice in November 2020 and October 2021. The crayfish were collected, the exposed pond bottom was treated by liming and left dry over winter. Predatory fish were stocked in the pond after refilling. Survival of the crayfish after the pond draining in 2021 was likely facilitated by up to 40 cm deep burrows found under large boulders. No specimens were observed in the nearby stream and marbled crayfish presence was not detected by environmental DNA screening in the stream and three other standing waters in the vicinity. The combined efforts resulted in a reduction in crayfish densities by an order of magnitude between successive harvests, but complete eradication of marbled crayfish was not achieved by 2023, as individual juveniles were captured during monitoring in the following two years. The perch-dominated fish stock apparently exerts a strong predation pressure that may control the crayfish population, as no marbled crayfish were captured during monitoring in 2024. The current status of the population is unclear, and further monitoring is warranted. Effective cooperation between different institutions and stakeholders has been successfully established, and the public and stakeholders have been educated about the risks of invasive species. However, with prolonged activities aiming to eradicate the crayfish, we also experienced decrease of public support for further radical actions. This experience provides a solid basis for future invasive crayfish management activities at sites with similar conditions.

 

Keywords: invasive species • management • biological invasions • freshwater • crustacean • macroinvertebrates 

 

Coutinho Carneiro and colleagues 2025

Coutinho Carneiro V, Schäfer I, Diaz-Larrosa JJ, Böhl E, Hahn T, Hempelmann J, Venkatesh G, Nagarajan S, Roy S, Ng YL, Böhl F, Zibek S, Lyko F. 2025. Establishment and characterization of biofloc culture for marbled crayfish. Frontiers in Aquaculture 4. https://doi.org/10.3389/faquc.2025.1580560

Abstract

Biofloc technology is an innovative aquaculture approach that enhances water quality and reduces waste through the development of beneficial microbial communities. Marbled crayfish (Procambarus virginalis) are a newly discovered freshwater crayfish species that are distinguished by asexual reproduction, a genetically homogeneous all-female population structure and considerable robustness. These traits are attractive features for closed-system aquaculture production, which also mitigates the invasive risk associated with the species. Here we describe the establishment and characterization of biofloc culture for marbled crayfish. Juvenile crayfish raised in biofloc systems displayed robust growth with a six-fold weight increase over three months, comparable with other crustaceans under similar conditions. Metagenomic analysis revealed that biofloc communities consisted mostly of beneficial Gammaproteobacteria and Bacillariophyceae, with variations by environmental factors, such as temperature and light exposure. DNA methylation profiling identified systematic changes in response to biofloc environments, highlighting the potential of DNA methylation analysis for environmental biomarker identification. Finally, nutritional analysis showed that biofloc-grown crayfish produced meat with a highly favorable protein-to-fat ratio, while their shells retained considerable amounts of chitin, an important raw material for bioplastics production. Taken together, our study is the first to establish marbled crayfish biofloc culture and to characterize the interaction between the animals and the production system.

Keywords: biofloc technology • sustainability • aquaculture • marbled crayfish • epigenetics •
chitin

 

Aluma and colleagues 2025

Aluma MO, Kaldre K, Strand DA, Hurt M, Pukk L. 2025. eDNA-based detection of invasive crayfish and crayfish plague in Estonia. Environmental DNA 7(3): e70107. https://doi.org/10.1002/edn3.70107

 

Abstract

 

In Estonia, three invasive North American crayfish species—Pacifastacus leniusculus, Faxonius limosus, and Procambarus virginalis—have been detected through the annual monitoring program. To protect Astacus astacus, the only native freshwater crayfish species in Estonia, rapid and effective conservation-based management actions are necessary. Recently, the environmental DNA (eDNA) approach has been increasingly used in Europe to detect crayfish species and the crayfish plague pathogen Aphanomyces astaci. Our study explored the potential of integrating the eDNA approach into ongoing annual monitoring programs for invasive crayfish species and A. astaci. We also evaluated the relationship between eDNA concentration and signal crayfish population density at a single location. We filtered 139 eDNA samples from 16 water bodies and screened them for A. astacus, P. leniusculus, and A. astaci using singleplex qPCR assays. A subset of the samples was also screened for P. virginalis and F. limosus. Crayfish eDNA was detected in nine out of 14 water bodies where presence was confirmed by trapping, resulting in a 64% detection efficiency. Detection of P. virginalis was only observed in samples with amplifications below the limit of detection, and A. astaci eDNA was found in only one water body hosting invasive crayfish species. Although we could not establish a convincing quantitative correlation between the estimated P. leniusculus eDNA concentration and crayfish population density, we conclude that the eDNA approach is promising and, with further optimization, it can be integrated into routine monitoring of crayfish and crayfish plague pathogen as a supplement to traditional trapping methods.

 

Keywords: None provided. 

Short course on Marmorkrebs

The Invasive Species Center is offering a short course on Marmorkrebs.

The course description:

This short course will provide an overview on crayfishes, with a particular focus on marbled crayfish biology, spread, and impacts.

Lesson 1: Introduction to Aquatic Invasive Species

Lesson 2: Introduction to Crayfishes

Lesson 3: Marbled Crayfish Biology

Lesson 4: Marbled Crayfish Impacts

Lesson 5: Preventing the Spread of Invasive Crayfishes

This course takes about 2 hours. Score an 80% on the final exam, and score a certificate of completion! 

The Center’s Instagram page has a discount code that lets you take the course for free until the end of May! If you happen to be reading this in June 2025 or later, sorry that it is no longer free, but should still be affordable.

External links

Invasive Species Training

Invasive Species Center on Instagram (contains discount code) 

Sheppard and Ricciardi 2025

Sheppard NLM, Ricciardi A. 2025. Influence of warming on the functional responses of invasive omnivores, Procambarus crayfishes. Canadian Journal of Fisheries and Aquatic Sciences 82: 1-8. https://doi.org/10.1139/cjfas-2024-0334

Abstract

The red swamp crayfish (Procambarus clarkii) and the marbled crayfish (Procambarus virginalis) are congeneric invasive species whose potential impacts in the Great Lakes basin have generated concern. In laboratory experiments, we tested the functional responses of these omnivores to two common food resources, insect larvae (Chironomus bloodworms) and aquatic macrophytes (Eurasian milfoil Myriophyllum spicatum), to gain predictive information on their per capita effects under present (18°C) and projected future (26°C) climate scenarios for the basin. The maximum feeding rate of P. virginalis was higher at 18°C than at 26°C when presented with bloodworms but did not differ between temperatures when presented with macrophytes. By contrast, the feeding rate of P. clarkii did not change with temperature for either food resource. Due to their larger mean size, P. clarkii exhibited higher rates of resource (bloodworm and macrophyte) consumption than P. virginalis at both temperatures. These results suggest that trophic impacts of P. virginalis will dampen with increased warming, whereas P. clarkii will sustain larger impacts irrespective of temperature within the range tested.

 

Keywords: None provided.