19 February 2019

Velisek and colleagues, 2018

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

09 February 2019

Andriantsoa and colleagues, 2019

Andriantsoa R, Töngesm S, Panteleit J, Theissinger K, Carneiro VC, Rasamy J, Lyko F. 2019. Ecological plasticity and commercial impact of invasive marbled crayfish populations in Madagascar. BMC Ecology 19: 8. https://doi.org/10.1186/s12898-019-0224-1



The marbled crayfish (Procambarus virginalis) is a monoclonal, parthenogenetically reproducing freshwater crayfish species that has formed multiple stable populations worldwide. Madagascar hosts a particularly large and rapidly expanding colony of marbled crayfish in a unique environment characterized by a very high degree of ecological diversity.


Here we provide a detailed characterization of five marbled crayfish populations in Madagascar and their habitats. Our data show that the animals can tolerate a wide range of ecological parameters, consistent with their invasive potential. While we detected marbled crayfish in sympatry with endemic crayfish species, we found no evidence for the transmission of the crayfish plague pathogen, a potentially devastating oomycete. Furthermore, our results also suggest that marbled crayfish are active predators of the freshwater snails that function as intermediate hosts for human schistosomiasis. Finally, we document fishing, farming and market sales of marbled crayfish in Madagascar.


Our results provide a paradigm for the complex network of factors that promotes the invasive spread of marbled crayfish. The commercial value of the animals is likely to result in further anthropogenic distribution.

Keywords: marbled crayfish • Madagascar • ecology • habitat diversity • crayfish plague • farming

02 February 2019

Kubec and colleagues 2019

Kubec J, Hossain MS, Grabicová K, Randák T, Kouba A, Grabic R, Roje S, Buřič M. 2019. Oxazepam alters the behavior of crayfish at diluted concentrations, venlafaxine does not. Water 11: 196. https://doi.org/10.3390/w11020196


Pharmaceutically active compounds are only partially removed from wastewaters and hence may be major contaminants of freshwaters. Direct and indirect effects on aquatic organisms are reported at dilute concentrations. This study was focused on the possible effects of environmentally relevant concentrations (~1 µg L−1) of two psychoactive compounds on the behavior of freshwater crayfish. Experimental animals exposed to venlafaxine did not show any behavioral alteration. Crayfish exposed to the benzodiazepine oxazepam exhibited a significant alteration in the distance moved and activity, and the effects were different when individuals were ready for reproduction. Results suggested that even the low concentration of selected psychoactive pharmaceuticals could alter the behavioral patterns of crayfish, as reported for other pharmaceuticals. These results provide new information about the possible adverse effects of pharmaceuticals at dilute concentrations. From previous knowledge and our results, it is obvious that different compounds have different effects and the effects are even specific for different taxa. Detailed studies are therefore needed to assess the possible ecological consequences of particular substances, as well as for their mixtures.

Keywords: environmental pollution • pharmaceuticals • freshwaters • crayfish