Marmorkrebs

Ham and colleagues 2026

noreply@blogger.com (Zen Faulkes) — Fri, 17 Jul 2026 16:12:28 +0000

Ham S-N, Nakata K, Soma R, Shirako T, Ishimori H, Ikehara K, Nakamura M, Kanno T, Asano M. 2026. Evidence of establishment and range expansion of the invasive marbled crayfish, Procambarus virginalis Lyko, 2017 (Decapoda: Astacidea: Cambaridae) in Okinawa, Japan. Journal of Crustacean Biology 46(3): ruag043. https://doi.org/10.1093/jcbiol/ruag043

Abstract

The invasive marbled crayfish, Procambarus virginalis Lyko, 2017, which reproduces by obligate parthenogenesis, has undergone rapid global expansion in recent decades. Records of this species in Japan, however, have been limited, and evidence of establishment and spread has remained scarce. We investigated the occurrence and population characteristics of P. virginalis in Okinawa, southern Japan. In addition to the previously reported population in a park pond in Naha City, we documented the species at two further sites: a channel-shaped biotope adjacent to an elementary school approximately 990 m from the park pond and a water source with its exact location withheld in Urasoe City, approximately 6.4 km from a different watershed. A total of 38 individuals were collected, including one adult carrying 43 juveniles at the channel-shaped biotope, providing clear evidence of successful reproduction. Size distributions indicate the presence of individuals at or near sexual maturity at all three sites. Genetic analyses revealed identical genotypes among individuals from all sites, indicating a clonal lineage and suggesting a shared origin or introduction from a common source. By contrast, variation in the presence of associated symbiotic ostracods among sites may provide insights into the introduction history of this species. These findings demonstrate a wider distribution of P. virginalis in Okinawa than previously recognized and suggest the potential for further spread. Given the high freshwater biodiversity and endemism in the region, continued spread of this species may pose a significant ecological risk, underscoring the need for monitoring and management.

Keywords: None provided.

More and colleagues 2026

noreply@blogger.com (Zen Faulkes) — Tue, 07 Jul 2026 21:34:53 +0000

Mor R, Kolodny O, Guy-Haim T. 2026. Trophic ecology of the invasive marbled crayfish in ephemeral streams of semi-arid environments. NeoBiota 108: 121-143. https://doi.org/10.3897/neobiota.108.183096

Abstract

The marbled crayfish (Procambarus virginalis) is an invasive, parthenogenetically reproducing species that has spread to freshwater ecosystems in more than 24 countries across North America, Europe, Africa, and the Middle East. To date, the trophic ecology of the marbled crayfish has been studied only in European lentic and lotic perennial ecosystems. This study aimed to shed light on the trophic ecology of the marbled crayfish in ephemeral streams of semi-arid environments in the Middle East. Three distinct habitats were compared using δ13C and δ15N stable isotope analysis to evaluate spatial variation in trophic position and resource use. A diet regime experiment was also conducted to test the impact of herbivorous and omnivorous diets on crayfish survival. In agreement with studies elsewhere, the analysis confirmed that P. virginalis functions as a flexible omnivore, occupying an intermediate trophic level (trophic position: 2.3–2.9), with the highest values observed during summer. The diet regime experiment indicated that juveniles can survive on various diets, with only small differences in survival rates among the three diets tested. The highest survival rate was observed under the poor plant-based diet. Adults and sub-adults also showed high survival rates under all tested diets, as well as some extent of cannibalism, which was amplified when they were fed purely plant-based diets. Cannibalism was primarily directed at small-sized juveniles (0–2 months old). In contrast, cannibalism among adults and sub-adults was very limited, even when they were reared at high densities.

Keywords: Bayesian mixing models • cannibalism • diet regime experiment • food web • isotopic niche breadth • Kaplan–Meier survival analysis • opportunistic feeding • stable isotope analysis

Shkurov and colleagues 2026

noreply@blogger.com (Zen Faulkes) — Sat, 04 Jul 2026 15:40:41 +0000

Shkurov AY, Ostras DA, Harkavenko VV. 2026. Effects of caffeine exposure on the behavior of the invasive marbled crayfish Procambarus virginalis. In: Pilay AP (Editor-in-chief), VetBioConnect: Young Scientists Conference, 3-4 June 2026, Kharkiv, pp. 91-93. https://doi.org/10.36016/VBC-2026 (Abstract only.)

Background. Caffeine is a widespread pharmaceutically active compound that enters surface waters mainly with municipal wastewater and may alter the behavior of aquatic organisms even at sublethal concentrations. Behavioral endpoints are especially important in ecotoxicology because changes in movement, shelter use, social interactions, and aggression can affect survival, dispersal, and population-level responses before mortality occurs. Crayfish are suitable model organisms for such studies because they demonstrate distinct spatial, social, and agonistic behavior that can be recorded and quantified under laboratory conditions. The marbled crayfish Procambarus virginalis is of particular interest because it is a parthenogenetic, highly plastic, and invasive species capable of rapidly establishing new populations from aquarium releases. For invasive hydrobionts, pollutant-induced behavioral changes may influence both individual stress tolerance and the ecological success of populations in transformed freshwater ecosystems. Previous studies have shown that psychoactive pollutants can modify locomotor activity, shelter-related behavior, and risk-taking in aquatic invertebrates, including crayfish. However, the behavioral effects of caffeine on P. virginalis remain insufficiently described. Therefore, short- term laboratory exposure combined with ethogram-based video analysis can provide useful preliminary data on how this invasive crayfish responds to caffeine contamination.

Aim. The aim of this study was to evaluate the effects of caffeine exposure on the behavioral structure of the invasive marbled crayfish Procambarus virginalis and to describe the temporal dynamics of changes in locomotor, anxiety-related, shelter- related, and aggressive activity over 24 hours.

Materials and methods. The study was carried out under laboratory conditions using video recording followed by ethogram analysis in BORIS software. Marbled crayfish were kept in an open 20 L container. In the control series, baseline behavior was recorded without the addition of any substance. In the experimental series, behavior was recorded after a single addition of caffeine at a dose of 200 mg per 20 L of water, corresponding to 10 mg/L. Behavior was assessed at 0, 6, 12, and 24 h after exposure. The duration and frequency of the following behavioral categories were analyzed: Move, Rest, Swim, Shelter, Wall, Field, Aggression, Attacking pose, and Ball of crayfish. The control and experimental observations were compared to identify changes in the distribution of behavioral forms and in the temporal structure of activity.

Results. In the control group, the behavioral profile remained relatively stable throughout the observation period: Rest predominated (60‒68% of the time), locomotor activity remained moderate (15‒22%), and aggressive or anxiety-related reactions were rare. During the first 10 min after caffeine addition, crayfish demonstrated pronounced hyperactivity and stress-related orientation: Move increased to 33.5%, Wall to 12.5%, Ball of crayfish to 18.9%, and Attacking pose to 18.7%. After 6 h, the behavioral pattern changed sharply: Rest reached 86.3%, whereas Aggression increased to 25.0% and Attacking pose to 25.7%, indicating motor exhaustion combined with persistent social tension. After 12 h, locomotor activity almost disappeared (Move 0.6%), while Attacking pose remained high (24.8%), suggesting postural tension under conditions of minimal mobility. After 24 h, Rest again predominated (73.9%), Aggression decreased to 6.6%, Attacking pose decreased to 4.2%, and episodic shelter use appeared.

Conclusions. Caffeine exposure caused a phase restructuring of the behavioral pattern of P. virginalis: from acute hyperactivity and anxiety through aggressive exhaustion to a relatively stable state of low-mobility adaptation. The results indicate that the behavior of marbled crayfish may be used as a sensitive indicator of caffeine and other pharmaceutical pollutants in aquatic environments. This approach can be applied in further studies of behavioral ecotoxicology of invasive hydrobionts and in the assessment of ecological risks in transformed freshwater ecosystems.

Keywords: marbled crayfish • Procambarus virginalis • caffeine • behavioral responses • invasive species • ecotoxicology.

Pipinić and colleagues, 2026

noreply@blogger.com (Zen Faulkes) — Mon, 15 Jun 2026 18:29:14 +0000

Pipinić K; Marn N; Hudina S. 2026. Effects of Multiple Stressors on the Crayfish– Pathogen Dynamics in Freshwater Ecosystems – A PhD Research Plan. In: Petrović Popović P, Popović M (eds.), Book of Abstracts of 10th Faculty of Science PhD Student Symposium. University of Zagreb Faculty of Science: Zagreb. https://www.croris.hr/crosbi/publikacija/prilog-skup/947642 (Direct link to PDF of conference abstract booklet: https://www.croris.hr/crosbi/publikacija/knjiga/940582)

Abstract

Host–pathogen dynamics have been extensively researched in model organisms of crayfish plague (Aphanomyces astaci Schikora, 1906) and freshwater crayfish. Invasive crayfish species introduced into European freshwater ecosystems are relatively tolerant of the disease due to their long coevolutionary history. They are considered vectors of crayfish plague when introduced to novel environments. Simultaneously, native populations are being decimated because they are more susceptible to the disease. A growing body of evidence suggests that similar coevolutionary processes are emerging between European crayfish and A. astaci. Host–pathogen dynamics are a key determinant of population viability, shaped by the complex interplay among the host, the pathogen, and the environment. However, how these interactions shift under global stressors such as climate change and pollution remains largely unexplored. The response to different stressors has been studied individually for crayfish plague, the native species Astacus astacus (Linnaeus, 1758), and the invasive species Procambarus virginalis Lyko, 2017. Our study aims to test the effects of multiple stressors (temperature and microplastic pollution) on the host–pathogen dynamic. We will experimentally test the exposure of A. astacus and P. virginalis to different temperature regimes, pathogen, and microplastics mixture, as well as combinations of the three stressors, and analyse their individual and joint effects on crayfish fitness (survival, growth rate, body condition and reproductive capacity). The results of our experiments will be used to train dynamic energy budget (DEB) models for both crayfish species. At the beginning of our study, we hypothesise that multiple stressors will have a greater impact on the fitness of the native species than on that of the invasive species. With DEB models, we will be able to predict tipping points at which significant metabolic responses and possible loss of native populations are expected. Tipping points may indicate conditions that negatively affect the invasive potential of P. virginalis. This poster will present the experimental design, aim, and expected results of our study.

Keywords: Aphanomyces astaci • Astacus astacus • Procambarus virginalis • modelling

Slusar and colleagues 2026

noreply@blogger.com (Zen Faulkes) — Sun, 14 Jun 2026 17:44:14 +0000

Slusar M, Muzhenko A, Kovalchuk S, Fedorovych Ye, Ishchuk O, Mamchenko V, Svitelskyi M. 2026. Comparative characteristics of physicochemical parameters of meat and biochemical composition of hemolymph in three species of crayfishes. Studia Biologica 20(2): 31-46. https://doi.org/10.30970/sbi.2002.887

Abstract

Background. Crayfish farming is a promising direction in the development of aquaculture. Compared with marine crustacean species, freshwater crayfish require lower cultivation costs, while their meat is regarded as an additive dietary delicacy with a high nutritional value. The aim of this study was to compare the morphological and physiological data (slaughter yield, taste quality, physicochemical composition of meat, and some biochemical indexes of hemolymph) of three species of adult crayfishes, i.e.Australian red claw crayfish (Cherax quadricarinatus), narrow-clawed crayfish (Astacus leptodactylus), and marbled crayfish (Procambarus fallax forma virginalis), which were cultivated in a recirculating aquaculture system.

Materials and Methods. Organoleptic and physicochemical methods were used to assess meat quality, while biochemical methods were applied to determine hemolymph parameters in the abovementioned crayfish species.

Results. The results showed that the edible portion relative to live weight was 15.16 ± 0.20 % in the Australian redclaw crayfish, 12.16 ± 0,21 % in the Marbled crayfish, and 9.40 ± 0,19 % in the Narrow-clawed crayfish. The highest protein content in meat was observed in marbled crayfish (17.4 ± 0.84 %). The highest fat content was registered in Australian redclaw crayfish (0.95 ± 0.024 %); for the marble crayfish, this value was 0.9 ± 0.03 %, and for the narrow-clawed crayfish, it was 0.9 ± 0.35 %. No
differences were found in carbohydrate content among the studied species; the value of this parameter was approximately 1.2 ± 0.02 % in all the crayfish species. The meat of Australian redclaw crayfish exhibited the highest energy value (76.1 ± 3.12 kcal/100 g), exceeding that of the other species by 1.3 – 2.2 kcal/100 g, marbled crayfish – 74.8 ± 3.69 kcal/100 g, and narrow-clawed crayfish ‒ 73.9 ± 3.52 kcal/100 g, respectively. In terms of hemolymph protein content, Australian redclaw crayfish showed the highest level (77.1 ± 2.87 g/L), for the narrow-clawed crayfish, this value was (64.9 ± 2.90 g/L), and for the marbled crayfish, it was (57.2 ± 2.41 g/L).

The highest calcium concentration in hemolymph was observed in narrow-clawed crayfish (9.52 ± 0.212 mmol/L), while comparable levels were recorded in Australian redclaw (7.99 ± 0.215 mmol/L) and marbled crayfish (7.42 ± 0.292 mmol/L). Differences in all studied indicators were considered statistically significant at p ≤ 0.05.

Conclusions. The study results obtained for Australian red claw crayfish, narrow-clawed crayfish and marbled crayfish allow us to evaluate their productivity and meat nutritional validity, as well as to propose the reference ranges of key indexes which can be used in optimizing aquaculture technologies and production of high-quality delicacies or supporting food products.

Keywords: crayfish aquaculture • Australian red claw crayfish (Cherax quadricarinatus) • narrow-clawed crayfish (Astacus leptodactylus) • marbled crayfish (Procambarus fallax forma virginalis) • slaughter yield • meat productivity • hemolymph • reference indexes

Poirier and colleagues 2026

noreply@blogger.com (Zen Faulkes) — Wed, 10 Jun 2026 12:47:03 +0000

Poirier LA, Pratt CJ, Hope E, Kingsbury S, McAlpine DF, LeBlanc F, Burbidge C. 2026. First record of the nonindigenous crayfish, Procambarus virginalis Lyko, 2017, in Nova Scotia, Canada. BioInvasions Records 15(2): 393-402. https://doi.org/10.3391/bir.2026.15.2.14

Abstract

Herein, we report the first record of the cambarid marbled crayfish (Procambarus virginalis Lyko, 2017) in the province of Nova Scotia, Canada. Originating from the pet trade in Germany, the marbled crayfish is a parthenogenic species that is known to be a rapid colonizer of multiple habitat types and can outcompete native species. Multiple collections of specimens were made during 2023 and 2024 in two small backyard ponds in the southwestern area of the province. Genetic confirmation was completed by sequencing a portion of the mitochondrial cytochrome c oxidase subunit 1 (CO1) gene using universal marine invertebrates PCR primers. A 100% match was obtained to publicly available DNA reference sequences. This species represents a potential threat to Nova Scotian waterways, as disruptions to food web organization are anticipated. With limited options for eradication and control, the potential for the mitigation or reversal of invasion impacts is low.

Keywords: marbled crayfish • range expansion • crawfish • introduction • vectors

Mengal and colleagues, 2026

noreply@blogger.com (Zen Faulkes) — Thu, 04 Dec 2025 19:10:00 +0000

Mengal K, Kor G, Siino V, Levander F, Niksirat H. 2026. Effects of acute cold and heat shocks on the protein profile of crayfish hemolymph: Implications for crustacean adaptation to thermal stress. Aquaculture Reports 46: 103265. https://doi.org/10.1016/j.aqrep.2025.103265

Abstract

Temperature, a key environmental stressor, can induce changes at the molecular levels in the body of living beings, which are necessary for adaptation and survival under altered conditions. We investigated the effects of acute cold (3 °C) and heat (32 °C) shocks on hemolymph protein profiles in marbled crayfish. Results showed that cold shock induced a metabolic shift toward glucose production by increasing enzymes for breaking down glycogen and upregulating enzymes related to glycolysis, such as glycogen phosphorylase, glyceraldehyde-3-phosphate dehydrogenase, enolase, and L-lactate dehydrogenase in the hemolymph of crayfish. The upregulation of proteins such as filamin-A, alpha-actinin, and tubulin beta may indicate that immune cells in the hemolymph strengthen their survival during cold stress through reinforcement of the cytoskeletal rigidity. Shifts in the abundance of immunity-related proteins such as masquerade-like and β-1,3-glucan-binding proteins suggest that the immune system of decapods can adapt to thermal stresses via remodeling the extracellular matrix and pattern recognition receptors, ultimately modulating host defense strategies by shifting between phagocytosis and melanization. Furthermore, the regulation of reproduction-associated proteins indicates that thermal shock may affect the capacity for reproduction. These findings offer insight into how decapods cope with thermal stresses and may support strategies to protect them in farmed environments, especially under climate change. Data are available via ProteomeXchange with identifier PXD065043.

Keywords: decapod • proteomics • temperature • marbled crayfish • thermal stress

Balzani and colleagues 2025

noreply@blogger.com (Zen Faulkes) — Wed, 26 Nov 2025 19:21:00 +0000

Balzani P, Musil M, Weiperth A, Bláha M, Kubec J, Ruokonen TJ, Ercoli F, Bányai ZM, Buřič M, Veselý L, Kouba A. 2025. Seasonal changes in trophic ecology of co-occurring freshwater invasive species at a thermal locality. Hydrobiologia 852(17): 4493-4512. https://doi.org/10.1007/s10750-025-05872-8

Abstract

We investigated the trophic ecology of three non-native crayfish species (the marbled crayfish Procambarus virginalis, the red swamp crayfish Procambarus clarkii and the spiny-cheek crayfish Faxonius limosus) and two non-native fishes (the eastern mosquitofish Gambusia holbrooki and the three-spined stickleback Gasterosteus aculeatus) from two sections of a thermal tributary of the Barát brook in Budapest (Hungary) over the four seasons using carbon and nitrogen stable isotope analysis. All crayfish species occupied an omnivore trophic position in almost all sections and seasons. On the other hand, both fishes had a predatory trophic position, with G. aculeatus occupying a higher position than G. holbrooki. These patterns are confirmed by the results of the mixing models, showing spatial and temporal changes in the diet composition. We also found interspecific differences in the crayfish trophic niche in both sections during summer and overlapped niches in the other occasions, while fish had always segregated niches. Crayfish showed interseasonal differences in the trophic niche in both sections, while fish showed seasonal niche shifts only in the upper section. Our results show a considerable plasticity in the trophic ecology of the studied non-native populations, suggesting that the temperature variability gradient has no important role in determining their trophic niche.

Keywords: Alien species • invasive species • stable isotopes • freshwater ecology • competition • predation

Art of invasive species

noreply@blogger.com (Zen Faulkes) — Wed, 26 Nov 2025 18:00:00 +0000

From Bluesky user charlie comes these art pieces of four invasive species, with Marmorkrebs in the middle:

The other three invasives are apple snails, round gobies, and European water chestnut plants.

Marin and colleagues, 2025

noreply@blogger.com (Zen Faulkes) — Sat, 25 Oct 2025 22:02:00 +0000

Marin IN, Statkevich SV. 2025. The first discovery of the invasive marbled crayfish Procambarus fallax (Hagen, 1870) in Crimea. Arthropoda Selecta 34(3): 359–364. https://kmkjournals.com/journals/AS/AS_Index_Volumes/AS_34/AS_34_3_359_364

Abstract

Data on the discovery of the invasive marbled crayfish Procambarus fallax (Hagen, 1870) (Decapoda: Cambaridae) in the western Crimea, in the lower streams of the Alma and Belbek rivers, is presented. This is the first report of its presence on the peninsula, adding another invasive species to the list in the Russian Federation. Phylogenetic analysis reveals that the crayfish found in Crimea share the same genetic haplotype as other invasive subpopulations from Europe, Sweden, Japan, and parts of Florida. The European subpopulation has a single haplotype, suggesting a relatively recent introduction, likely from a single parent within its native range in Florida. In the case of the lower reaches of the Alma and Belbek rivers, we propose a hypothesis based on the possible involvement of large migratory birds, such as hissing swans and ducks, and plants attached to their paws in the spread of juvenile crayfish to nearby water reservoirs.

Keywords: invasion • Decapoda • Crustacea • crayfish • COI mtDNA • Crimean Peninsula

Toutain and colleagues 2025

noreply@blogger.com (Zen Faulkes) — Sun, 10 Aug 2025 13:02:00 +0000

Toutain M, Soto I, Oficialdegui FJ, Balzani P, Cuthbert RN, Huber AF, Haubrock PJ, Kouba A. 2025. Claw loss and the prey preferences of an invasive crayfish. NeoBiota 100: 91-108. https://doi.org/10.3897/neobiota.100.149248

Abstract

Predator-prey relationships underpin the stability of ecosystems but can be perturbed by numerous factors, such as biological invasions. Crayfish readily colonize new ecosystems and their impacts can modify food webs or ecosystem functioning. However, while crayfish exert high levels of predation pressure handling prey with their claws, claw loss is also common in their populations, which could mediate prey selection pressures. Here, we investigate how the number of claws in the marbled crayfish Procambarus virginalis modulates its preferences for two different available prey: Chironomus plumosus and Gammarus fossarum. We showed that the food preference of P. virginalis was mainly for soft, less mobile prey, such as C. plumosus, with significantly fewer G. fossarum (harder, more mobile prey) being killed. This preference was largely independent of claw presence but depended on the availability of prey, with fewer G. fossarum being targeted as the number of claws decreased. Our results highlight the complexity of predator-prey ecological relationships in invaded freshwater ecosystems and show that some biotic factors, such as the quantity and type of prey available, need to be taken into account in order to better understand their role in ecosystem dynamics.

Keywords: Chironomus plumosus • choice experiment • feeding preference • Gammarus fossarum • macroinvertebrate community • prey preference • Procambarus virginalis

Ložek and colleagues 2025

noreply@blogger.com (Zen Faulkes) — Thu, 10 Jul 2025 21:51:00 +0000

Ložek F, Staňová AV. 2025. Conjoined twins in marbled crayfish Procambarus virginalis Lyko, 2017 (Decapoda: Astacidea: Cambaridae). Journal of Crustacean Biology 45(2): ruaf033. https://doi.org/10.1093/jcbiol/ruaf033

Abstract

We report the first observation of viable conjoined twins of marbled crayfish Procambarus virginalis Lyko, 2015 during postembryonal development. Two cases of hatched juveniles were identified incidentally among normal hatchlings from eggs of laboratory-stocked marbled crayfish during an experiment unrelated to the observation. In the first case, each twin had its own anteroposterior body axis with dorsal adhesion in the cephalothorax region, referring to conjoined twins pattern duplicitas completa. They lived for 37 days post-hatch in the laboratory and survived moulting into the third postembryonal stage. The second case involved conjoined twins with unequal-sized embryos that died before the first moulting. Despite the rarity of the observation, the two cases occurred close in time and among a relatively low number of eggs, suggesting that the frequency of conjoined twins should be experimentally verified, as marbled crayfish could represent a promising model for its study.

Keywords: None provided.

Kronenberger and colleagues 2025

noreply@blogger.com (Zen Faulkes) — Tue, 01 Jul 2025 03:27:00 +0000

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

noreply@blogger.com (Zen Faulkes) — Sat, 21 Jun 2025 20:34:00 +0000

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

noreply@blogger.com (Zen Faulkes) — Fri, 06 Jun 2025 14:21:00 +0000

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

noreply@blogger.com (Zen Faulkes) — Wed, 28 May 2025 21:19:00 +0000

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

noreply@blogger.com (Zen Faulkes) — Wed, 28 May 2025 21:18:00 +0000

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

noreply@blogger.com (Zen Faulkes) — Thu, 15 May 2025 21:47:00 +0000

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

noreply@blogger.com (Zen Faulkes) — Fri, 04 Apr 2025 19:39:00 +0000

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.

Talking Marmorkrebs to the streets

noreply@blogger.com (Zen Faulkes) — Tue, 25 Mar 2025 21:26:00 +0000

Pleased to hear that Marmorkrebs were part of a show promoting outdoor activities,

Brianna Naklicki from the Ontario Federation of Anglers and Hunters was handing out information booklets to visitors passing by. She works for the organization’s invasive species awareness program.

On a table in front of her are jars containing examples of species of concern in the province, including zebra mussels and marbled crayfish.

Her job at the show was to spread awareness about invasive species around lakes and forests to all who will listen.

Ontario is, so far, the only place in North America where Marmorkrebs have been found in the wild, and is the largest jurisdiction to ban Marmorkrebs.

External links

Outdoor show hooks nature lovers into shopping local

Update on Marmorkrebs in Warsaw, Poland

noreply@blogger.com (Zen Faulkes) — Tue, 25 Feb 2025 17:13:00 +0000

A couple of recent news articles are reporting on the presence of Marmorkrebs in Warsaw. This location was already in my map of Marmorkrebs introductions. A bioblitz located seven individuals in Morskie Oko Park back in 2019.

Fast forward six years to 2025, and the population is estimated at 100,000 crayfish.

The article notes that there are removal efforts, but they can’t drain the pond, so culling them requires catching them by hand or trap. And in typical local media style, they stress the expense.

I do appreciate the safety warning:

The expert emphasized that rakes do not attack a person if they are not provoked to do so.

I don’t know of any crayfish that voluntarily attacks people with anything more than a pinch.

External links

Wpuścił raka do stawu w Warszawie. "Doprowadził do niepowstrzymanej ekspansji" (He released a crayfish into a pond in Warsaw. “He led to unstoppable expansion”)

Warszawa zmaga się z inwazją raka marmurkowego. Ekspert ostrzega (Warsaw is struggling with marbled crayfish invasion, expert warns)

Photo by Adrian Grycuk - Own work, CC BY-SA 3.0 pl, https://commons.wikimedia.org/w/index.php?curid=101324805

Everyday sexism

noreply@blogger.com (Zen Faulkes) — Sat, 22 Feb 2025 22:39:00 +0000

Always nice to stumble across a video mentioning marbled crayfish. I’m kind of used to them showing some other random crayfish species, but this one has a new thing that made me pause.

This video is titled, “This guy copies himself 2,000 times!”

Since marbled crayfish are all female, a better title would be, “This gal copies herself 2,000 times.”

Eiler and colleagues 2025

noreply@blogger.com (Zen Faulkes) — Wed, 05 Feb 2025 21:13:00 +0000

Eiler A, Stensrud E, Osman O. 2025. Detection of marbled crayfish Procambarus fallax. protocols.io. https://dx.doi.org/10.17504/protocols.io.q26g78199lwz/v1

Abstract

Taqman QPCR assay for marbled crayfish Procambarus fallax.

Keywords: None provided.

The Crayfish Almanac

noreply@blogger.com (Zen Faulkes) — Thu, 30 Jan 2025 15:12:00 +0000

Don’t know how I missed this last year, but Michigan State University released Great Lakes Almanac to Invasive Crayfish.

It has one of the best short identification guides for Marmorkrebs I’ve seen. Click to enlarge!

Marbled crayfish (or marmokrebs) originated in the aquarium trade and are often called the self-cloning crayfish. All marbled crayfish are female and the offspring are clones. This species is of high concern because a single individual can produce an entire population in a short time.

This species has a distinct marbling pattern, but other species may look similar. Male crayfish with this pattern are not marbled crayfish.

To determine if its a female, look for a round pocket-like feature located on the underside between the last pair of walking legs. This is the sperm pouch (called an ‘annulus ventralis’) .

External links

Great Lakes Almanac to Invasive Crayfish

Golubev and colleagues 2024b

noreply@blogger.com (Zen Faulkes) — Fri, 24 Jan 2025 21:21:00 +0000

Golubev AP, Ulashchyk EA, Bodilovskaya OA. 2024. Modeling the growth of the invasive river crayfish species Procambarus virginalis (Decapoda, Astacidea) under different temperature conditions. https://www.researchgate.net/publication/387918897_Modeling_the_growth_of_the_invasive_river_crayfish_species_Procambarus_virginalis_Decapoda_Astacidea_under_different_temperature_conditions

Abstract

In the marbled crayfish Procambarus virginalis, the dependence of the duration of inter-larval intervals on body weight and the magnitude of body weight gains for individual inter-larval intervals in the temperature ranges 15.3–17.9 °С, 7.5–18.9, 19.1–20.8, 21.0–22.8, 22.9–25.2 and 25.3–28.9 °С was determined. The growth curves of individuals in these temperature ranges and the sum of effective temperatures (Sef) of individuals during juvenile growth and breeding periods were calculated from these data. The average Sef value for the juvenile period of P. virginalis (until newborn individuals reach a body weight of 1.4 g) in the studied temperature ranges is 4316 degree·days at the biological zero temperature of 7.6 °C. For the breeding period (until reaching the body weight from 1.4 g to the limit weight of 15 g) – respectively 10630 degree·days and 3.0 °C. Based on the annual dynamics of mean monthly temperatures in six continental water bodies within the invasive range of P. virginalis (Sweden, Belarus, Germany, Slovakia, North Macedonia and Malawi), Sef values were calculated for the periods of the year during which juvenile growth and reproduction of sexually mature individuals are possible. In temperate water bodies located in Sweden, Belarus, Germany and Slovakia, Sef values during the juvenile growth period vary between 1083 and 2099 degree·days. In the more southern body of water in Northern Macedonia, this value reaches 2990 degree·days, and in the tropical African body of water in Malawi it reaches 7076 degree·days. Consequently, newborn individuals of P. virginalis, which in water bodies of the temperate zone of Europe hatch in the first half of summer, can reach sexual maturity only in the third summer of life, and in a tropical water body – already in the first summer of life. Sef values for periods of the year favorable for the growth of sexually mature individuals in the studied water bodies of Europe increase from 2031 degree·days (water body in Sweden) to 4657 degree·days (water body in Northern Macedonia). In the tropical water body of Malawi, this figure reaches 8058 degree·days, i.e. the maximum life span of P. virginalis in this water body does not exceed two years. Nevertheless, throughout the entire range, sexually mature individuals of P. virginalis are capable of producing no more than 2–5 clutches of eggs per life cycle.

Note: The ResearchGate page includes a link to the DOI 10.46646/2521-683X/2024-4-18-34. At the time of this writing in January 2025, this link is not working. I will update this entry with more information if I learn more.