18 March 2019

International Crayfish Conference 2019

The International Conference on Crayfish will be in Europe this year, organized by Blue Centre Gotland, Swedish University of Agricultural Sciences. and University of Eastern Finland. This conference is open to both researchers and crayfish farmers.

For more information, contact Gunilla Rosenqvist (gunilla.rosenqvist@geo.uu.se) or Lennart Edsman (Lennart.edsman@slu.se).

External links

Internationell kräftkonferens 27 - 30 augusti 2019

07 March 2019

Bradshaw, 2019

Bradshaw L. 2019. The genetic authentication of Malagasy crayfish samples. South Carolina Junior Academy of Science. 270. https://scholarexchange.furman.edu/scjas/2019/all/270


The marbled crayfish (Procambarus virginalis) is a relatively new species that emerged by macromutation nearly 30 years ago from Procambrus fallax. Despite its short existence, it has already become an invasive species because of its ability to reproduce clonally and its environmental adaptability. The marbled crayfishes’ high adaptability allows it to thrive in diverse conditions throughout the globe. It is very important to correctly identify marbled crayfish because, to do epigenetic research with them, we need to know the epigenetic profile. This experiment analyzed two Malagasy crayfish samples to test if they were Procambarus virginalis. This work was necessary because it is the only way to distinguish between different crayfish species besides morphology which is subjective. DNA was isolated from the abdominal tissue of 2 unknown crayfish samples, analyzed by PCR, and compared to known DNA reference sequences. The results for crayfish #1 were inconclusive because the insert was not incorporated by the plasmid, but it was confirmed that crayfish #2 was Procambarus virginalis. Future work on the marbled crayfish will be to help establish a methylome sequence. This methylome sequence will show average methylations to the DNA, helping further understand the epigenetics of clonal tumor evolution.

Keywords: None provided.

Banned in Japan?

The Japanese newpaper The Mainichi is reporting that Marmorkrebs could soon be added to Japan’s list of “Invasive Alien Species.”

The article notes that there have been a couple of isolated cases of Marmorkrebs found in the wild in Japan (as noted on the map of introductions). The article provides the first confirmation I know of – unsurprising though it is – that Marmorkrebs are readily available in the pet trade there.

Looking at the Ministry’s page on invasive species, crayfish are already regulated to some degree. The PDF of regulated species say all crayfish (“Any species of the families Astacidae, Cambaridae, and Parastacidae”) are “Required to have a Certificate Attached during their importation in order to verify their types.” But this does nothing once a species is in the national pet trade and being distributed within Japanese borders.

Marmorkrebs would join all the species of Astacus and Cherax, the signal crayfish (Pacifastacus leniusculus), and the rusty crayfish (Faxonius rusticus, still listed as Orconectes in the Japanese documents) as an invasive.

External links

Environment ministry plans to add marbled crayfish to list of invasive species

05 March 2019

Stara and colleagues, 2019

Stara A, Kubec J, Zuskova E, Buric M, Faggio C, Kouba A, Velisek J. 2019. Effects of S-metolachlor and its degradation product metolachlor OA on marbled crayfish (Procambarus virginalis). Chemosphere 224: 616-625. https://doi.org/10.1016/j.chemosphere.2019.02.187


Increasing production of energy crops in Europe, mainly maize and rapeseed, has altered patterns of pesticide use in recent decades. The long-term effects of S-metolachlor (S-M) and of its metabolite metolachlor OA (M-OA) at the environmentally relevant concentration of 4.2 μg  L−1 and at 42 μg  L−1 (ten-fold concentration) on marbled crayfish (Procambarus virginalis) were evaluated in a 28-day exposure and after a subsequent 28-day recovery period. Indicators assessed were behaviour; biochemical haemolymph profile; oxidative and antioxidant parameters of gill, hepatopancreas, and muscle; and histology of hepatopancreas and gill. Results showed biochemical haemolymph profile (lactate, alanine aminotransferase, aspartate aminotransferase, inorganic phosphate), lipid peroxidation in hepatopancreas, and antioxidant parameters (catalase, reduced glutathione, glutathione S-transferase) of hepatopancreas and gill of crayfish exposed to S-M and M-OA to significantly differ from controls (P < 0.01). Antioxidant biomarker levels remained different from controls after a 28-day recovery period. Differences in behaviour including speed of movement and velocity, and histopathological damage to gill and hepatopancreas were associated with S-M and M-OA exposure and persisted after 28 days in S-M- and M-OA-free water. Results suggest harmful effects of low concentrations of S-M and its metabolite M-OA on non-target organisms and provide information for assessing their effects at environmentally relevant concentrations.

Keywords: herbicide • metabolite • crustacean • biomarkers • histology • recovery

19 February 2019

Velisek and colleagues, 2019

Velisek J, Stara A, Zuskova E, Kubec J, Buric M, Kouba A. 2019. Effects of s-metolachlor on early life stages of marbled crayfish. Pesticide Biochemistry and Physiology 153: 87-94. https://doi.org/10.1016/j.pestbp.2018.11.007


The effects of s-metolachlor chronic exposure at concentrations of 1.1 μg/L (maximal real environmental concentration in the Czech Republic), 11 μg/L (environmental relevant concentration) and 110 μg/L on early life stages of marbled crayfish (Procambarus virginalis) was evaluated under laboratory conditions. All s-metolachlor exposures resulted in higher mortality, delay ontogenetic development with accompanied slower growth and excited behaviour (increase of total distance moved and walking speed). Significantly lower superoxide dismutase, catalase, glutathione S-transferase activity and reduced glutathione level was observed at two higher tested concentrations (11 and 110 μg/L) of s-metolachlor compared with the control. S-metolachlor in concentrations 110 μg/L showed alteration of the tubular system of hepatopancreas including focal disintegration of tubular epithelium and notable reduction in epithelial cells number, especially B-cells. In conclusion, potential risk associated with using of s-metolachlor in agriculture, due to effects on non-target aquatic organisms as documented on early life stages of marbled crayfish in this study, should be taken into account.

Keywords: herbicide • Procambarus virginalis • ontogenetic development • behaviour • antioxidant enzymes • toxicity test

Hossain and colleagues, 2019

Hossain MS, Kubec J, Kouba A, Kozák P, Buřič M. 2019. Still waters run deep: marbled crayfish dominates over red swamp crayfish in agonistic interactions. Aquatic Ecology 53(1): 97-107. https://doi.org/10.1007/s10452-019-09675-7


Intra- and interspecific interactions contribute to the successful establishment and consequent spreading of species in the environment, which became particularly apparent in the context of ongoing biological invasions. The parthenogenetic marbled crayfish, Procambarus virginalis, Lyko 2017 is recently recognized as an emerging invader due to its high adaptability, fast growth, early maturation, and high fecundity. The present study explored the interaction patterns of size-matched (including 15 body parts morphometry evaluation) pairs of marbled crayfish and red swamp crayfish Procambarus clarkii, a well-known highly aggressive and widely distributed invader of freshwater ecosystems. Despite this, marbled crayfish won significantly more fights and establish dominancy in more cases in both premature and mature experimental trials. Premature red swamp crayfish pairs were more active in contact and fight initiation than mature. In mature, the dominance over female red swamp crayfish was 100%, in males it reached 60%. Premature marbled crayfish dominated in more than 75% pairs. Agonistic behaviour and intensity of fights significantly dropped after establishment of dominance in particular (size and sex) pairs. Therefore, we confirmed that sex and age (size) have effects on agonistic behaviour in crayfish as well as the dominance of marbled crayfish within similarly sized specimens. Despite described behavioural patterns, we can expect that the situation in the potential sympatric occurrence of both species will not be as clear as found in experimental conditions due to greater maximal size of red swamp crayfish.

Keywords: competition • dominance • interaction • Procambarus virginalisProcambarus clarkii

16 February 2019

Nothing like a Dane: the European invasion continues

Another European country has become home to Marmorkrebs. The Copenhagen Post Online is reporting a single Marmorkrebs was found on the main body of Denmark, Jutland, near the town of Skive.

It’s been a few months since I updated the map of Marmorkrebs introductions, so I supposed this was due. It feels like Marmorkrebs in every European nation is as inevitable as no deal Brexit at this point. Maybe Lichtenstein can hold out.

External links

Self-fertilising invasive crayfish discovered in Denmark