02 May 2016

African crayfish

The Conversation hosts a good post by Ana Nunes about the introduction of crayfish into Africa. Marmorkrebs make a brief cameo appearance (with an incomplete name):

Another species that bears mentioning is the marbled crayfish or “Marmokrebs” (Procambarus fallax) (sic). It was introduced to Madagascar for mysterious reasons, but there may be a link with a road building project carried out by foreign contractors in 2003/2004. In 2005, biologists at the University of Antananarivo noticed it being sold in markets close to the capital.

This particular crayfish has a peculiar history: nobody knows where it comes from. It simply appeared in the German aquarium trade in about 1995. It is also the only decapod in the world known to be able to reproduce by parthenogenesis – a female is able to reproduce without being fertilised by a male. This means that a single individual is sufficient to start a whole new population. As such, this species seems very likely to pose a serious threat to freshwater biodiversity in Madagascar.

Even though it focuses on one continent, it is a very nice lay summary of the issues around crayfish introductions.

External links

Freshwater crayfish: the forgotten invaders wreaking havoc across Africa

Pictured: Lake Naivasha, site of a Procambarus clarkii introduction. Picture from here.

19 April 2016

Korša, 2016

Korša A. 2016. Epifauna on freshwater crayfish (Crustacea: Decapoda) in Croatia. Master's thesis, Department of Biology, University of Zagreb.http://digre.pmf.unizg.hr/id/eprint/4635


The research of epifauna on freshwater crayfish as basibionts was conducted during springsummer (sic) 2014. and 2015. Epizoic community was examined from five different crayfish: three autochtonous species Astacus astacus, Austropotamobius pallipes, A. torrentium and two introduced, invasive species Pacifastacus leniusculus and Procambarus fallax f. viriginalis. The aims of this research were: (i) to analyze epizoic community living on freshwater crayfish, (ii) to compare epifauna living on crayfish with surrounding fauna living on sediment and periphyton, (iii) to compare epifauna between crayfish species, especially between autochthonous and allochthonous species. The results of statistical analysis indicated a significant difference between epifauna and fauna of sediment and periphyton. 44 different taxa of epifauna was recorded. The most abundant group was Ciliophora with most common species Vorticella campanula and Epistylis sp. The most diverse group was Rotifera with most common species Lepadella parasitica and Dicranophorus hauerianus. Branchiobdellidanas were confiremd (sic) as common crayfish epibionts and for the first time nort (sic) american species Xirogiton victoriensis has been recored (sic) in Croatia. Catenulida, Gastrotricha, Nematoda, Bivalvia, Hirudinea, Tardigrada, Crustacea, Hydrachnidia and Chironomidae were also recorded living on freshwater crayfish. Results of NMDS and Cluster analyses showed the eparation (sic) of epifauna from autochotnous and allochthonous crayfish and also the separation of epifauna between autochthonous species. Results of statistical analyses showed significant difference between epifauna and fauna of sediment and periphyton. It can be concluded that the whole epizoic community composition established on a particular crayfish is species-specific and can be different between basibiont species.

Keywords: autochtonous and alochtonous species • epibionts • basibionts • Ciliophora • Rotifera • Xirogiton victoriensis

14 April 2016

Vogt, 2016b

Vogt G. 2016. Fate of glair glands and oocytes in unmated crayfish: a comparison between gonochoristic slough crayfish and parthenogenetic marbled crayfish. BioRxiv: 8 April 2016. http://dx.doi.org/10.1101/047654 [Pre-print]


In the period before spawning, freshwater crayfish develop glair glands on the underside of the pleon. These glands produce the mucus for a tent-like structure in which the eggs are fertilized and attached to the pleopods. Long-term observation of females of slough crayfish, Procambarus fallax, kept in the laboratory without contact to males revealed that glair glands developed in late winter and early autumn of each year. However, in contrast to mated females, unmated females never formed fertilization tents and never spawned. Their glair glands persisted for an unusually long period of time and disappeared only during the next moult. Inhibition of spawning and mucus release from the glair glands suggests that the females had information on sperm availability and saved resources when unmated. Marbled crayfish, Procambarus virginalis, a parthenogenetic descendant of slough crayfish, developed glair glands and spawned in spring and autumn as their mother species although they never mated. These findings suggest that on their way from gonochorism to parthenogenesis regulation of spawning and glair gland activity has been decoupled from mating and sperm transfer.

Keywords: None provided.

Travel awards for International Association of Astacology 2016

The symposium of the International Association of Astacology will be held from 5-8 September 2016 in Madrid, Spain. The deadline for Student Travel Awards for the IAA21 in Spain is approaching (30 April 2016). Please find information in www.iaa21rjb.es, and submit your applications to dieguez@rjb.csic.es. 5-6 Scholarships (US$500 each) will be awarded to IAA students attending to the IAA21st Symposium.

05 March 2016

Novitsky and Son 2016

Novitsky RA, Son MO. 2016. The first records of Marmorkrebs [Procambarus fallax (Hagen, 1870) f. virginalis] (Crustacea, Decapoda, Cambaridae) in Ukraine. Ecologica Montenegrina 5: 44-46. http://www.biotaxa.org/em/article/view/19706/19060


Without abstract. Excerpt:

During last decades expansions of three invasive alien decapods (Rhithropanopeus harrisii , Eriocheir sinensis Milne-Edwards, 1853 and Macrobrachium nipponense (De Haan, 1849)) have been reported from Ukrainian inland waters (Son et al. 2013).

In 2015 two localities of a new alien species – Marmorkrebs or marbled crayfish Procambarus fallax (Hagen, 1870) f. virginalis were observed (Fig. 1).

Keywords: None provided.

01 March 2016

Mystery cameo

Marmorkrebs makes a brief cameo appearance in a new paper about that evergreen biological topic, species concepts:

More recently MARTIN et al. (2010), discussing the way parthenogenetic population derives from bisexual species (the concrete case of Cambarus fallax, the so-called Marble crayfish), considered that for such uniparental populations the phylogenetic species concept should apply, because parthenogenesis is an apomorphic trait within a given phylogenetic lineage with bisexual ancestors.

What surprising to me is the species name. They are not the first authors to omit the “forma virginalis”, but I think they are the first to put Marmorkrebs in the genus “Cambarus.” This is puzzling since they cite the paper that clearly says Marmorkrebs are “Procambarus.”

Mysteries of editing.


Danielopol DL, Tabacaru IG. 2015. The species concept, thematic subject in natural sciences – the scientific approaches of Emil G. Racovitza and Nicolae Botnariuc. Travaux de L`Institut de Speologie "Emile Racovitza" 54: 3-24. http://www.speotravaux.iser.ro/15/art01.pdf

17 February 2016

Has the European Union regulated Marmorkrebs?

A forthcoming paper by Boets and colleagues says (my emphasis):

On a European level, a list of invasive alien species of EU concern that cannot be traded, kept, or bred and of which the future dispersal should be limited through preventive actions (e.g. pathway regulation) or active management has recently been approved. Chinese mitten crab and five species of crayfish (O. limosus, O. virilis, P. leniusculus, P. clarkia and Procambarus fallax f. virginalis) are on the list of EU concern and therefore regulated.

I went looking for this approved list. On the European Commission page on invasive alien species, I found some risk assessments, which included Marmorkrebs, here. But nothing seemed to fit the bill of an approved species “blacklist” that is mentioned above.

I will keep looking to see what I can find.

Update, 19 February 2016: Emailing the authors got me a link to this page (in Dutch). And indeed, “invasive crayfish,” including Marmorkrebs, are definitely listed, with an identification sheet to help non-specialists tell the invasive from the natives. I was still curious about the actual legislation, however. It appears to have come into effect 2 January 2016. Using Google translate on this page, I learned:

There is currently a significant difference in policies implemented by the Member States of the European Union, which measures are often too fragmented to lead to effective results. So it makes little sense that one country by conducting a thorough control of some invasive species, if the neighbors do not. To arrive at a more unified and effective approach was therefore defined by the European regulation.

Indeed, the variation in legislation is one part of the problem I’ve written about. But what’s the rule for Marmorkrebs pet owners

There is a total ban on the possession, trade, transport, production and release of these species in the wild. Pet animals which were the entry into force of the Regulation in possession may be held until natural death, provided that the animals are kept in a closed environment, can not escape and can not reproduce. Kind used for the sake of commercial purposes, can be kept for two years after the inclusion of the species on the list under similar conditions.

The “cannot reproduce” clause is... um... problematic for Marmorkrebs owners. They all reproduce! So it’s not clear to me if this means that pet Marmorkrebs people have now are grandfathered in or not. I suspect not.

The penalties will be set by the individual member states.

As the saying goes, “Big if true.” This appears to be a major step towards limiting the spread and ownership of Marmorkrebs in the pet trade in Europe.

This would be a perfect time to start doing research on the availability of crayfish in the pet trade. If the legislation is effective, crayfish availability should decline over the next couple of years. As far as I know, only one paper has tried to systematically examine the effect of legislation on the trade in crayfish: Magalhães and Andrade (2015) found a decrease, but not the elimination, of crayfish in the pet trade, and concluded the ban was not effective.


Boets P, Brosens D, Lock K, Adriaens T, Aelterman B, Mertens J, Goethals PLM. Alience macroinvertebrates in Flanders (Belgium). Aquatic Invasions 11: in press. http://www.aquaticinvasions.net/2015/ACCEPTED/AI_2016_Boets_etal_correctedproof.pdf

Magalhães, A.L.B. and Andrade, R.F. 2015 Has the import ban on non-native red swamp crayfish (Crustacea: Cambaridae) been effective in Brazil? Neotropical Biology and Conservation 10: 48-52. http://dxd.oi.org/10.4013/nbc.2015.101.07

External links

Alien invasive species - European Commission