24 November 2023

RIP Günter Vogt

I recently learned from the CRUST-L mailing list that Günter Vogt in this last June. He was one of the earliest and most prolific authors studying Marmorkrebs and a wonderful booster of this blogging project. I was lucky enough to meet him at SICB some years ago and had a wonderful talk. He will be missed.

28 September 2023

Hamr 2023

Cover of Crayfish News 45, issue 1-2, with marbled crayfish on cover.

Hamr P. 2023. First record of the marbled crayfish in Canada/North America. Crayfish News 45(1-2): 1, 3. https://www.astacology.org/docs/cn/CrayfishNews_45(1-2)_hr.pdf (Direct link to PDF)


Without abstract. First paragraph: 


Suspected marbled crayfish (Procambarus virginalis) were first reported in Southern Ontario in October 2021. The reports came from a Burlington City Park and were made by a naturalist (Ms. N. Bucik) as well as park staff who observed and photographed individual crayfish walking on a nature path as well as on a nearby football (soccer) pitch. All the reports were made near three stormwater ponds in the park where it was suspected the crayfish came from. (The identity of the crayfish was subsequently confirmed by EU crayfish experts when I showed the photos at IAA 23 in the Czech Republic in July 2022). 

Keywords: None provided.

16 September 2023

Vogt, 2023

Cover of Current Zooology volume 69 number 4
Vogt G. 2023. Phenotypic plasticity in the monoclonal marbled crayfish is associated with very low genetic diversity but pronounced epigenetic diversity. Current Zoology 69(4): 426-441. https://doi.org/10.1093/cz/zoac094


Clonal organisms are particularly useful to investigate the contribution of epigenetics to phenotypic plasticity, because confounding effects of genetic variation are negligible. In the last decade, the apomictic parthenogenetic marbled crayfish, Procambarus virginalis, has been developed as a model to investigate the relationships between phenotypic plasticity and genetic and epigenetic diversity in detail. This crayfish originated about 30 years ago by autotriploidy from a single slough crayfish Procambarus fallax. As the result of human releases and active spreading, marbled crayfish has established numerous populations in very diverse habitats in 22 countries from the tropics to cold temperate regions. Studies in the laboratory and field revealed considerable plasticity in coloration, spination, morphometric parameters, growth, food preference, population structure, trophic position and niche width. Illumina and PacBio whole-genome sequencing of marbled crayfish from 19 populations in Europe and Madagascar demonstrated extremely low genetic diversity within and among populations, indicating that the observed phenotypic diversity and ability to live in strikingly different environments is not due to adaptation by selection on genetic variation. In contrast, considerable differences were found between populations in the DNA methylation patterns of hundreds of genes, suggesting that the environmentally induced phenotypic plasticity may be mediated by epigenetic mechanisms and corresponding changes in gene expression. Specific DNA methylation fingerprints persisted in local populations over successive years, but there is presently no information as to whether these epigenetic signatures are inherited or established anew in each generation and whether the recorded phenotypic plasticity is adaptive or non-adaptive.

Keywords: phenotypic plasticity • environmental adaptation • whole genome sequencing •
epigenetics • DNA methylation • marbled crayfish

Open access logo

Carneiro and colleagues 2023

Cover to "BioInvasion Records"

Carneiro VC, Galil B, Lyko F. A voyage into the Levant: the first record of a marbled crayfish Procambarus virginalis (Lyko, 2017) population in Israel. BioInvasion Records 12(3): 829-836. https://doi.org/10.3391/bir.2023.12.3.18


The marbled crayfish, Procambarus virginalis (Lyko, 2017) is a novel parthenogenetic freshwater species that has rapidly colonized diverse habitats in Europe and Madagascar. Here we describe the first wild population of marbled crayfish in the Middle East. Numerous specimens, including gravid females, were collected in the waters of a spring on Mt. Carmel, Israel. The results from phenotypic, morphometric and genetic analyses showed the close relationship with other known populations, consistent with the clonal structure of the global marbled crayfish population. Our findings represent a considerable expansion of the known distribution range and further illustrate the role of anthropogenic activities in the dispersal of marbled crayfish.

Keywords: invasive species • freshwater crayfish • freshwater ecology • anthropogenic dispersal

Open access

Faiad and colleagues, 2023


Faiad SM, Williams MA, Goodman M, Sokolow S, Olden JD, Mitchell K, Andriantsoa R, Jones JPG, Andriamaro L, Ravoniarimbinina P, Rasamy J, Ravelomanana T, Ravelotafita S, Ravo R, Rabinowitz P, De Leo GA, Wood CL. 2023. Temperature affects predation of schistosome-competent snails by a novel invader, the marbled crayfish Procambarus virginalis. PLOS ONE 18(9): e0290615. https://doi.org/10.1371/journal.pone.0290615


The human burden of environmentally transmitted infectious diseases can depend strongly on ecological factors, including the presence or absence of natural enemies. The marbled crayfish (Procambarus virginalis) is a novel invasive species that can tolerate a wide range of ecological conditions and colonize diverse habitats. Marbled crayfish first appeared in Madagascar in 2005 and quickly spread across the country, overlapping with the distribution of freshwater snails that serve as the intermediate host of schistosomiasis–a parasitic disease of poverty with human prevalence ranging up to 94% in Madagascar. It has been hypothesized that the marbled crayfish may serve as a predator of schistosome-competent snails in areas where native predators cannot and yet no systematic study to date has been conducted to estimate its predation rate on snails. Here, we experimentally assessed marbled crayfish consumption of uninfected and infected schistosome-competent snails (Biomphalaria glabrata and Bulinus truncatus) across a range of temperatures, reflective of the habitat range of the marbled crayfish in Madagascar. We found that the relationship between crayfish consumption and temperature is unimodal with a peak at ~27.5°C. Per-capita consumption increased with body size and was not affected either by snail species or their infectious status. We detected a possible satiation effect, i.e., a small but significant reduction in per-capita consumption rate over the 72-hour duration of the predation experiment. Our results suggest that ecological parameters, such as temperature and crayfish weight, influence rates of consumption and, in turn, the potential impact of the marbled crayfish invasion on snail host populations.

Keywords: None provided.

Open access

16 August 2023

Kaur and colleagues 2023

Cover to Ecology and Evolution, Volume 13, Number 8

Kaur D, Iqbal A, Soto I, Kubec J, Buřič M. 2023. Effects of chemical cues and prior experience on predator avoidance in crayfish. Ecology and Evolution 13(8):e10426. https://doi.org/10.1002/ece3.10426


Multisensory stimuli provide organisms with information to assess the threat present in the surroundings. Olfactory cues show dominance over other sensory modalities in the aquatic environment. The impact of chemical predator cues combined with experiences gained (learning) in species without previous contact is not fully understood. We investigated the foraging and shelter-seeking behaviour of naïve and experienced marbled crayfish Procambarus virginalis juveniles in response to the chemical signals of pumpkinseed Lepomis gibbosus alone and in combination with alarm chemicals produced by preyed-upon conspecifics. Naïve and experienced (previously exposed to pumpkinseed predation) juveniles were stocked in an arena with shelter and feed and exposed (1) to water from a tank containing a predator actively feeding on conspecifics, (2) water from a tank with predator only and (3) water only as control. Crayfish exposed to the combined stimuli avoided the inlet zone and gravitated to shelter zone of the arena to a greater extent than did those exposed to predator-only cues and the control. Regardless of the treatment, experienced crayfish showed significantly reduced interest in feeding. Our findings imply that crayfish response to threat-associated odours with the greatest potency when visual or tactile cues are present, while previous encounters with predators may make them more cautious.  

Keywords: alarm cues • crayfish • fish • infochemicals • kairomones • predation

Open access

05 August 2023

Be on the lookout for Marmorkrebs, Ontario! Marmorkrebs finally found in North America

Marbled crayfish recovered from pond in Burlington, OntarioBurlington Today is reporting that Marmorkrebs have been found in Burlington, Ontario.

The details are hazy.


Marbled crayfish – an aquatic invasive species that is prohibited in the province – has been found in the Burlington area.


That’s the extent of actual reporting. The rest of the article is background information.

Edit, 6 August 2023: A Burlington Post article is a little more expansive.  It gives a general location (a city park).

Previously, another marbled crayfish was reported in the area on iNaturalist. (I actually went to where the iNaturalist sighting was to look around, but heard people had already looked and found nothing.) 


This Burlington marbled crayfish sighting is also on iNaturalist, from Premek Hamr, also known as “Dr. Crayfish.” Premek has extensive experience with Ontario crayfish, so it’s not as though this is an Ontario native being misidentified.


On Twitter, Hamr has been sharing pictures of multiple individuals, including juveniles. This indicates there is a breeding population at this location.


Ontario just banned marbled crayfish last year.

While this is a watershed moment in the worldwide invasive status of marbled crayfish, it is something that has been expected for a long time. It’s mostly surprising in that it didn’t happen a few years ago.

The map of Marmorkrebs introductions has been updated.

External links

Marbled crayfish sighting in iNaturalist


Premek Hamr on Twitter: Onetwo , three, four


Be on the lookout for marbled crayfish in the Burlington area (Burlington Today)


‘Capable of cloning’: Invasive crayfish found in Burlington pond (Burlington Post)

‘Capable of cloning’: Invasive crayfish found in Burlington pond (Hamilton Spectator

Ontario Natural Resources and Forestry on Twitter

Related posts

Ontario prohibits Marmorkrebs