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

14 January 2019

Shinji and colleagues, 2019

Shinji J, Gotoh H, Miyanishi H, Lavine MD, Lavine LC. 2019. The activin signaling transcription factor Smox is an essential regulator of appendage size during regeneration after autotomy in the crayfish. Evolution & Development 21(1): 44-55. https://doi.org/10.1111/ede.12277


Members of the phylum Arthropoda, comprising over 80% of total animal species, have evolved regenerative abilities, but little is known about the molecular mechanisms mediating this process. Transforming growth factor β (TGF‐β) signaling mediates a diverse set of essential processes in animals and is a good candidate pathway for regulation of regeneration in arthropods. In this study we investigated the role of activin signaling, a TGF‐β superfamily pathway, in limb regeneration in the crayfish. We identified and cloned a downstream transcription factor in the activin pathway, Smox, and characterized its function with regard to other elements of the activin signaling pathway. Gene knockdown of Smox by RNAi induced regeneration of complete but smaller pereopods after autotomy. This indicates that activin signaling via Smox functions in regulation of pereopod growth and size. The expression levels of both Smox and the activin receptor babo were closely correlated with molting. The expression level of Smox increased when babo was knocked down by RNAi, indicating that Smox and babo transcription are linked. Our study suggests that the Babo‐Smox system in activin signaling is conserved in decapods, and supports an evolutionary conservation of this aspect of molecular signaling during regeneration between protostomes and deuterostomes.

Keywords: None provided.

31 December 2018

2018 was the second best year ever for Marmorkrebs research

It’s time for this blog’s longest running tradition! (Okay, the only tradition, if we’re honest.) It’s the eleventh annual look at trends in Marmorkrebs publishing!

As mentioned back in 2016, the graph above includes journal articles and book chapters. There were no book chapters this year, however. I feel compelled to add a second graph, plotting only the journal articles. The graph below is much more what this year felt like:

A barnstormer of a bumper crop of a year that was much busier than any before. But 2016 comes out on top because a single book dropped with a bunch of articles on Marmorkrebs. But several of those were reviews, and that they all came out in one volume meant it felt like one event instead of nine. Honestly, I think the activity in Marmorkrebs papers coming out in journals is a better indicator of the expansion of the field.

This year saw the biggest Marmorkrebs paper of all time published, at least as measured by its Altmetric score. Gutekunst and colleagues had two major findings in one paper:

  1. Announcing the sequencing of the Marmorkrebs genome, the first for a decapod crustacean.
  2. Documenting the spread of Marmorkrebs in Madagascar since their detection about a decade earlier.

What was strange, though, was that almost none of the news coverage (of which there was a lot) focused on either of those two things. Most focused on the fact that cloning crayfish were a thing, which we have known from 2003. Some focused on the invasive nature of Marmorkrebs, but tended to talk about their spread in Europe rather than Madagascar. Having the first decapod crustacean genome, which might have been the biggest long term result from this paper, was very underplayed.

Another trend was researchers started to adopt the name Procambarus virginalis, after the name was proposed three years ago. The initial 2015 proposal was a “naked name” (nomen nuden in taxonomic lingo) with none of the typical descriptive work to accompany the new Linnean name, and the community generally used Procambarus fallax forma virginalis in 2016 and 2017. But having a proper taxonomic paper published in 2017 seems to have turned the tide, and P. virginalis seems to now be the accepted name in the community.

With the trendline continuing to head up, and two papers with 2019 cover dates already out, the state of Marmorkrebs research is strong.

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2008 was the best year ever for Marmorkrebs research
2009 was tied for the best year ever in Marmorkrebs research
2010 was the best year ever for Marmorkrebs research
2011 was not the best year ever for Marmorkrebs research
2012 was an average year for Marmorkrebs research
2013 was the second best year ever for Marmorkrebs research
2014 was a good year for Marmorkrebs research
2015 was the best year ever for Marmorkrebs research
2016 was the best year ever for Marmorkrebs research
2017 was the second best year ever for Marmorkrebs research