2016 was the best year ever for Marmorkrebs research

And it was the best by a long, long ways.

There are not only more papers, but they are coming from more places, too. In the early 2000s, papers were almost exclusively from western Europe and particularly Germany. Now, eastern Europe and Japan are regularly publishing Marmorkrebs papers in addition to the more established western European and American research programs. And the mix of papers is broad, too, with research on Marmorkrebs as invasive species, cellular biology, and behaviour.

Since I started this blog, it’s been a tradition for me to have a graph showing how many papers on Marmorkrebs were published compared to previous years. But making this year’s graph was trickier than before, because there are more kinds of research products out there than before.

In the past, I’ve included journal articles and book chapters. But by this year, I’ve been blogging pre-prints, master’s theses, and conference abstracts in addition to regular old articles and chapters. I’ve thought about whether to include these research products, and decided to include journal articles and book chapters only. In theory, pre-prints and master’s theses should be published later, so excluding them avoids the problem of inflating the publication rates.

As I noted last year, I also had the confusion of a book published in 2015 that had a 2016 cover date (Freshwater Crayfish, which I was involved with). Those book chapters are included in 2016, which bumps up the total for the year considerably. But 2016 would still be the best year ever for Marmorkrebs research even if if you removed the seven Freshwater Crayfish chapters from the total.

The book publication does mean that it will be hard for 2017 to top 2016 in the number of crayfish papers. The overall trend, however, shows no signs of flattening.


Related posts

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

By “invasive species,” do you mean crayfish or Daleks?

When you’re a scientist, sometimes you forget that other people see the world through different lenses than you do. And sometimes you have that point hammered home in no uncertain terms.

Last week, the American White House released an executive order from outgoing President Barack Obama about invasive species.

As someone who has written about invasive species, I thought, “Ho hum, routine sorts of stuff.”

But because I had shown interest in invasive species, Google suggested this page to me:

NO JOKE! Obama signs executive order to ‘Safeguarding the nation from an INVASIVE SPECIES’

Wait, what? Why is this page showing the American president and a SF style alien? My emphasis:

Obama has pushed through an act called “Safeguarding the Nation from the Impacts of Invasive Species.” The interesting thing about this presidential order (see full text below) is the legal wording of the document leaves a lot up for suspicion. The article was left purposely vague, it seems.

There are a few reasons for this. The first could be simply so the article can be interpreted for years to come. The second is a little more malicious and slightly terrifying. An invasive species in the document is vaguely defined as an organism that disrupts an ecosystem. Because of this, some are speculating that this last order of 2016 is meant to protect from alien invasions, and purposely set some guidelines for the next presidency.

It has been shown in the news that the government is getting closer to telling its people what is actually out in space. If the planet needs protection for these beings, it will make sense that they would be motivated to tell the people, and also motivated to write an article to set up pretenses to protect the Earth. This is only my opinion, but I hope that some of my readers will do some investigation. Something strange is happening within the government.

Now I wonder: when I have said, “invasive species,” how often have non-scientists heard, “alien invaders”? It kind of makes sense to me now. Anyone who watches science fiction will probably heave heard aliens described as “difference species.” Indeed, there’s a horror movie franchise whose name plays around with that ambiguity:

But despite that, it never occurred to me that someone might think “species” is synonymous with “extraterrestrial” rather than meaning “type of organism.”

Now, when I write about potential negative impacts of crayfish introductions, I have to think of other phrases to use so that when I say “invasive species,” people don’t automatically leap to this:

Related posts

Crayleks!

External links

Executive Order -- Safeguarding the Nation from the Impacts of Invasive Species
NO JOKE! Obama Signs Executive Order To 'Safeguarding The Nation From An INVASIVE SPECIES'

Listing a species as “injurious”

The Center for Invasive Species Prevention was about to ask the US Fish and Wildlife Service to add Louisiana red swamp crayfish (Procambarus clarkii) to a list of “injurious” species.

In the petition, the CISP says the red swamp crawfish does not provide any essential economic or other benefits that outweigh their current and potential harm to the United States. ...

If the proposed changes are adopted then it could limit or prohibit the sale and export of crawfish across state lines.

But the day after I read the news article announcing that, the Center backed off. Judging from the news story and memo, it looked like the petition caused a bit of a freak out among people who sell the beast for food.

I think it’s a very interesting window into regulation. Biologically, there is no question that P. clarkii is a problematic invasive. It’s caused problems worldwide, from being farmed for aquaculture and is one of the most widely distributed crayfish in the pet trade (one of the “big six” worldwide). I think you would be hard pressed to find any biologist specializing in crayfish or invasive species that wouldn’t consider P. clarkii an extremely successful and problematic invasive species.

But there is so much established trade already within the U.S. that it is completely unsurprising that there would be pressure to not change anything.

The food industry is large and powerful. So is the pet industry, the other main mover of crayfish today. And the trade is largely unregulated, particularly for invertebrates. Although crayfish are not particularly popular in the US as pets right now, the European experience in the 1990s shows that there could easily be a “boom” in interest.

External links

Are crawfish an invasive species? Warning: contains annoying auto-play video
Statement of the Center for Invasive Species prevention on withdrawing its proposal to the U.S. Fish and Wildlife Service to add the red swamp crayfish to the Lacey act for further analysis

Picture by Michael Bok on Flickr.

Call for crustacean papers: The Journal of Crustacean Biology

Journal of Crustacean Biology is well established, peer-reviewed journal published by The Crustacean Society. But there are changes afoot!

The journal is moving over to Oxford University Press at the start of the new year (Volume 37, Number 1). The journal will be getting a new format (presumably in line with other Oxford University Press journals like Integrative and Comparative Biology), colour covers, and will have an open access option – I think for the first time for the journal.

Society members pay no page charges, will get reduced open access fees, and free access to the Journal’s digital archive. Plus, society members will a 25% discount on Oxford University Press books. Given the cost of academic books, it will only take a few book purchases to make membership in the Society pay for itself!

Current editor-in-chief Peter Castro encourages the submission of review articles, short research notes, and articles on techniques and methods. You can email him for the new author’s instructions.

The journal has published several Marmorkrebs papers already (Kawai et al. 2009; Martin & Scholz 2012; Shinji et al. 2016), so hopefully it will publish more Marmorkrebs papers there under the auspices of the new publisher!

External links

Journal of Crustacean Biology
The Crustacean Society website

Call for crustacean papers: Nauplius

Nauplius is a peer-reviewed, open access journal published by Sociedade Brasileira de Carcinologia, also known as the Brazilian Crustacean Society. Its mandate is to cover all aspects of crustacean biology. It has clocked up a more than 20 year track record, but, like so many fine regional journals, was new to me (embarrassingly 😔).

Because it is sponsored by the Society, there are no article processing fees for publishing in the journal. Remember this journal for the next time someone says, “But I can’t afford to publish open access.” Really? You can’t afford free?

The new feature of this journal is that they have moved to a continuous publication model, Papers are available online shortly after acceptance, rather than being held back for the delivery of a bundled issue.

It might be a good venue to submit research on Marmorkrebs!

External links

Nauplius website
Nauplius on Facebook

Ninth International Crustacean Congress announcement and call for symposia

The 9th International Crustacean Congress (ICC IX) will be held in Washington, DC from 22-25 May 2018, at the Smithsonian Institution and the Renaissance Hotel. This marks the first time this meeting has been in the USA and at the venerable Smithsonian Institution.

The ICC IX Organizing Committee is requesting ideas and leaders for symposia for this important meeting.

Symposia can be half days or full days and can be on any broad topic associated with crustacean biology or related research whether basic or applied. Broad ideas that would include Crustacea combined with other taxa, are welcome. Possible areas for symposia development include genomics/transcriptomics, reproduction, biodiversity, palaeontology, microbiomes, parasites and evolution, invasion biology, aquaculture, fisheries, and so on.

Please communicate symposium ideas to Chris Tudge at ctudge@american.edu.

More information to follow, including important dates and the ICC IX website.

Picture: Famed carcinologist Mary Jane Rathbun in the Smithsonian. Picture from here.

Takahashi and Nagayama, 2016

Takahashi K, Nagayama T. 2016. Shelter preference in the Marmorkrebs (marbled crayfish). Behaviour 153(15): 1913-1930. http://dx.doi.org/10.1163/1568539X-00003399

For many animals, shelters are valuable source to hide from predators. To know acquisition of adequate shelter is important to understand social interactions of animals. Preferences for types of shelter used by the Marmorkrebs (marbled crayfish) were analysed behaviourally. Individual crayfish were presented with a choice between two PVC pipes with four different internal diameters (XL, L, M and S). The time spent in each shelter and the number of times crayfish entered each shelter were measured. Preference ranks of crayfish were XL = L = or > M > S. Our experiments strongly suggested that crayfish chose shelters based first on the diameter of the entrance, and then based on the length of the shelter. Crayfish recognised adequate shelters by visual cues under light conditions and utilised tactile cues from their antennae under dark conditions.

Keywords: recognition • visual cue • crayfish • shelter choice • thigmotactic cue

Vogt, 2016c

Vogt G. 2016. Direct development and posthatching brood care as key features of the evolution of freshwater Decapoda and challenges for conservation. In: Kawai, T. and Cumberlidge, N. (eds.), A Global Overview of the Conservation of Freshwater Decapod Crustaceans, pp. 169-198. Springer International Publishing: Cham. http://dx.doi.org/10.1007/978-3-319-42527-6_6

Abstract

Direct development and posthatching brood care are among the key evolutionary adaptations of decapod crustaceans to life in fresh water. Direct development is obligatory in aeglid anomurans, primary freshwater crabs, and freshwater crayfish. It also occurs in some species of secondary freshwater crabs and freshwater shrimps. Posthatching brood care is the rule in aeglids, primary freshwater crabs, and crayfish, infrequent in secondary freshwater crabs, and rare in freshwater shrimps. Extended brood care is most intense in crayfish where it includes the attachment of hatchlings by a safety line, and specific behaviours of the mother and her offspring. Direct development and posthatching brood care are associated with reduced dispersal and reduced gene flow among populations, which may explain the high degree of endemism and speciation in freshwater decapods. Due to the reduced dispersal and recolonization abilities aeglids, primary freshwater crabs, and crayfish that live in stressed freshwater habitats may face a higher threat of extinction than do species of amphidromous shrimps and crabs that can undergo long-distance migrations.

Keywords: freshwater Decapoda • direct development • posthatching brood care • evolutionary adaptation • speciation • endemism • conservation

Kawai and Crandall, 2016

Kawai T, Crandall KA. 2016. Global diversity and conservation of freshwater crayfish (Crustacea: Decapoda: Astacoidea). In: Kawai T, Cumberlidge N (eds.), A Global Overview of the Conservation of Freshwater Decapod Crustaceans, pp. 65-114. Springer International Publishing: Cham. http://dx.doi.org/10.1007/978-3-319-42527-6_3

Abstract

The number of species in the three families of freshwater crayfish worldwide (Astacidae, Cambaridae, and Parastacidae) are updated by region. These are: Astacidae, western North America (5 species) and Europe (5 species), Cambaridae, eastern North America and Mexico (423 species) and Asia (6 species), and Parastacidae, Oceania (153 species), South America (12 species), and Madagascar (7 species). The conservation status of 611 species of crayfish worldwide is discussed, based on global assessments from the IUCN (International Union for Conservation of Nature) Red List protocols as well as regional assessments on governmental endangered species lists. The current threats to endangered species of crayfish include habitat destruction, water diversion, pollution, and threats from exotic species of crayfish (such as Pacifastacus leniusculus, Procambarus clarkii and Cherax) that have been introduced to other parts of the world where they are having an increasing impact. New threats posed by the parthenogenetic marbled crayfish Procambarus fallax f. virginalis to freshwater ecosystems in Europe and Madagascar are also discussed.

Keywords: alien crayfish • conservation • species diversity • IUCN Red List

2017 Gherardi Prize

The applications for 2017 Francesca Gherardi Memorial Prize are now open. This prize goes to young researchers who study invasive aquatic animals. The application deadline is 30 November 2016.

More information here.

Kotovska and colleagues, 2016

Kotovska G, Khrystenko D, Patoka J, Kouba A. 2016. East European crayfish stocks at risk: arrival of non-indigenous crayfish species. Knowledge and Management of Aquatic Ecosystems 417: 37. http://dx.doi.org/10.1051/kmae/2016024

Abstract

An increasing number of non-indigenous crayfish species (NICS) of apparently pet trade origin have become established particularly in Europe. Especially alarming are recent confirmation of two distantly separated marbled crayfish Procambarus fallax f. virginalis populations in Ukraine and indications of more North American cambarids present in the local pet market. The present study aimed to investigate crayfish species availability within the Ukrainian pet trade together with the climate match and risk they represent to the freshwater ecosystems generally and indigenous crayfish species in particular. Altogether, 15 NICS belonging to all three crayfish families were detected. Considering their origin, availability, probability of establishment, invasiveness and further aspects, marbled crayfish and red swamp crayfish Procambarus clarkii appear to be potentially the most troubling. Available information obtained from the pet trade in ornamental crayfish as a whole demonstrates that the broad availability of NICS most probably overlaps the vast majority of European indigenous crayfish species distribution, including the endemic thick-clawed crayfish Astacus pachypus, which occupies only a limited area that is situated critically close to established marbled crayfish populations. Negative effects of NICS on freshwater ecosystems as a whole can be also expected.

Key words: Ukraine • pet trade • ornamental animal • invasiveness • aquarium

Then we take Berlin

A new article in Verbundjournal reports that Marmorkrebs are establishing themselves in lakes around the German capital of Berlin.

It’s a passing reference in an article by grad student Stefan Linzmaier, who is studying Marmorkrebs as an example of how an invasive species impacts the ecology of a system. I will not claim that I am entirely clear of all the details of Stefan’s ongoing research, since I am reading the article through the help of Google Translate, which can have... interesting interpretations of text.

The map of Marmorkrebs introductions has been updated accordingly. Hat tip to Gerhard Scholtz.

References

Linzmaier S. 2016. Vom Aquarium in den See. Verbundjournal 106: 14-15. http://www.fv-berlin.de/oeffentlichkeitsarbeit/verbundjournal-1/pdfs/verbund106.pdf

Yazicioglu and colleagues, 2016

Yazicioglu B, Reynolds J, Kozák P. 2016. Different aspects of reproduction strategies in crayfish: a review. Knowledge and Management of Aquatic Ecosystems 417: 33. http://dx.doi.org/10.1051/kmae/2016020

Abstract

Study of the reproductive strategy of crayfish species is of great importance in the current astacological world. Crayfish are among the largest freshwater invertebrates, and as keystone species, they are able to regulate the structure of the benthic fauna in the freshwaters, demonstrating different ecological strategies and life spans ranging up to 20+ years. In order to bring together the various pieces of information related to this issue, this overview of published scientific reports was conducted. The majority of crayfish species studied show sexual dimorphism, with approximately equal numbers of males and females. However, over some decades numerous observations have been made for a few species that may have different modes of reproduction, such as hermaphroditism or intersex (e.g. Cherax quadricarinatus, Samastacus spinifrons, Parastacus virilastacus and Pacifastacus leniusculus) and parthenogenesis (only Procambarus fallax f. virginalis). A recent study showed a new case of parthenogenesis as apomictic parthenogenesis (only Orconectes limosus). In addition, there are many investigations into the reproduction biology of crayfish, including using eyestalk ablation or androgenic gland ablation under various lab conditions and hybridization under natural conditions (e.g. Astacus astacus X Astacus leptodactylus, Orconectes rusticus X Orconectes propinquus). There are also some chemical factors which could possibly affect the reproduction system of crayfish in the wild.

Keywords: Crustacea • parthenogenesis • intersex • hybridization

The two sides of marbled crayfish

The International Association for Astacology meeting was recently held in Spain, and a nice press release about the two major lines of research on Marmorkrebs: as an unwanted invasive, and as a wanted model organism. I draw similar comparisons in my own chapter.

Between Google Translate and a little guesswork, I think the press release reads something like this:

• This North American species is reshaping ecosystems by killing fish or molluscs on the one hand, and on the other hand, is used for studies related to cancer thanks to their particular genetics.
• Researchers Pavel Kozák and Frank J. Lyko presented studies about this crustacean at the 21st International Symposium of Astacology.

The marble crayfish (Procamborus (sic) fallax) is a curious exotic species, as has been disclosed during the 21st International Symposium of Astacology, which takes place at the Royal Botanical CSIC Garden. Like the strange case of Dr. Jekyll and Mr. Hyde, it shows two sides: a positive, because thanks to their particular genetics, it is used for cancer-related studies; and the other less pleasant, because it is an invasive species that is ravaging different ecosystems.

Researchers Pavel Kozák from the Faculty of Fisheries and Protection of Waters of the University of South Bohemia in the Czech Republic, and Frank J. Lyko, from the Cancer Research Center of Heidelberg in Germany, are working on two projects related to marbled crayfish. They presented their studies on this species from the point of view of ecology and reproduction (Kozák) and genetics (Lyko).

According to the Czech researcher, his project initially focused on the impact of invasive species on native species of crayfish, but as the project continued, this deepened to include the interaction between this invasive species and their impact on other invasive species, such as amphibians or fish.

The researcher Kozák focuses on two significant events. “First, marbled crayfish are destroying fish, molluscs, and macroinvertebrates, and ultimately, it is reshaping the entire ecosystem. Second, this invasive species is more powerful than other larger species, thus refuting the claim that the larger species tend to be more aggressive.”

Meanwhile, the German researcher Frank J. Lyko notes that the genetics of marbled crayfish reproduction, i.e., the females create clones of themselves, “is a model species to implement our work on cancer, since there is only one genome to study, hence its importance for medical science.”

Devastating effects

However, Lyko coincides with his Czech colleague Kozák in the “devastating effects” of marbled crayfish, such as in Madagascar where they have destroyed almost all the habitat where they have been, before making the leap to other countries. The first crayfish in Europe were found in Germany in 1995, and by 2010, it was established in nature, especially Central Europe. In the short term, also has changed the habitat of this area.

The two researchers also agree that, given that its eradication is impossible, citizens of the areas where this species is found be educated to know how easily it reproduces and the consequences of their invasion. They also requested legislation regulating the introduction of new species and greater control of ornamental trade, both in physical stores and the sale online, because it is very easy to get this species for aquariums, and their reproduction is immediate and unlimited.

Finally, for Czech researcher Pavel Kozák, this highlighted the work of the Royal Botanic Garden-CSIC of Madrid, which conducts research related to crayfish plague and supports students doing projects on astacology.

When I went to the International Association of Astacology meeting in Missouri in 2010, I think I was one of the first to talk about Marmorkrebs at that venue. At least, several people told me it was news to them. It is nice to see more research at this preeminent crayfish meeting on Marmorkrebs, and making its way into the public.

External links

Cangrejo mármol, una curiosa especie invasora con dos caras (Roughly: Marbled crayfish, a curious invasive species with two faces)

Shinji and colleagues, 2016

Shinji J, Miyanishi H, Gotoh H, Kaneko T. 2016. Appendage regeneration after autotomy is mediated by Baboon in the crayfish Procambarus fallax f. virginalis Martin, Dorn, Kawai, Heiden and Scholtz, 2010 (Decapoda: Astacoidea: Cambaridae). Journal of Crustacean Biology 36(5): 649-657. http://dx.doi.org/10.1163/1937240x-00002458

Abstract

Autotomy is an adaptive response in which animals escape from predators by shedding their own appendages. It is made possible by the presence of an efficient mechanism for regeneration. Decapod crustaceans frequently exhibit excellent abilities to regenerate complete pereopods in just a few molts following autotomy. The molecular basis of regeneration pereopods in decapods remains unclear. We identified the primary structure of Baboon (Babo), a type I TGF-β superfamily receptor involved in the activin pathway, in the crayfish, Procambarus fallax f. virginalis Martin, Dorn, Kawai, Heiden and Scholtz, 2010. Molecular cloning revealed that babo possesses three splice variants. The expression levels of the functional babo transcript did not show increases during regeneration. RNA interference (RNAi) targeting a common region of the babo sequence, however, caused a reduction in regenerated pereopod lengths. No loss or reduction in a specific article was observed. Instead, the regenerated legs were smaller but retained the morphology and proportions of regenerated legs from control animals. Babo thus appears to control the growth, but not the pattern, of legs during the regeneration process in decapod crustaceans.

Keywords: signaling • marmorkrebs • marbled crayfish • receptor • TGF-β • activin

Marenkov and colleagues, 2016

Marenkov O, Fedonenko E, Naboka A. 2016. Impact of low-molecule acidic peptides on growth and histological structure of inner organs of marbled crayfish Procambarus fallax (Hagen, 1870) f. virginalis. International Letters of Natural Sciences 56: 1-6. http://dx.doi.org/10.18052/www.scipress.com/ILNS.56.1

Abstract

The results of studies on the effects of low molecular weight acidic solution peptides on the growth and development of the marbled crayfish artificial cultivation. An increasing weights of juvenile freshwater crayfish under the influence of dietary supplement “Albuvir” drug. With the use of histological methods of research, found the impact of 0.01% solution of the drug on the state of the marbled crayfish lobules of hepatopancreas and fat cells. Developed a method for growing juvenile freshwater crayfish with “Albuvir”, which allows to increase the weight gain of crustaceans on 24.3–27.2% and reduce the level of cannibalism at 20%.

Keywords: Albuvir • marbled crayfish • Marmorkrebs • Procambarus fallax

Kato and colleagues, 2016

Kato M, Hiruta C, Tochinai S. 2016. The behavior of chromosomes during parthenogenetic oogenesis in Marmorkrebs Procambarus fallax f. virginalis. Zoological Science 33(4): 426-430. http://dx.doi.org/10.2108/zs160018

Abstract

Parthenogenetic oogenesis varies among and even within species. Based on cytological mechanisms, it can largely be divided into apomixis (ameiotic parthenogenesis) producing genetically identical progeny, and automixis (meiotic parthenogenesis) producing genetically non-identical progeny. Polyploidy is common in parthenogenetic species, although the association between parthenogenesis and polyploidy throughout evolution is poorly understood. Marmorkrebs, or the marbled crayfish, was first identified as a parthenogenetic decapod and was tentatively named as Procambarus fallax f. virginalis. Previous studies revealed that Marmorkrebs is triploid and produces genetically identical offspring, suggesting that apomixis occurs during parthenogenetic oogenesis. However, the behavior of chromosomes during the process of oogenesis is still not well characterized. In this study, we observed parthenogenetic oogenesis around the time of ovulation in P. fallax f. virginalis by histology and immunohistochemistry. During oogenesis, the chromosomes were separated into two groups and behaved independently from each other, and one complete division corresponding to mitosis (the second meiosis-like division) was observed. This suggests that parthenogenetic oogenesis in Marmorkrebs exhibits gonomery, a phenomenon commonly found in apomictic parthenogenesis in polyploid animals.

Keywords: parthenogenesis • apomixis • chromosome behavior • oogenesis • Marmorkrebs • gonomery

Nominations for 2017 Gherardi Prize

It is once again time to work on applications for the Francesca Gherardi Memorial Prize! You are eligible if:

• You study aquatic invasive species;
• You’re young (less than 40);
• Don’t have a permanent position (a grad student or post-doc, usually)

Applications are due 30 November 2016.
External links

Francesca Gherardi Memorial Prize

Incoming: Biology and Ecology of Crayfish

A new crayfish book is out! Biology and Ecology of Crayfish has ten chapters of freshwater crustacean goodness. Marmorkrebs make a few cameo appearances in chapters marked with an asterisk.

1. Taxonomy and identification. 
2. Population genetics of crayfish: endangered and invasive species. *
3. Crayfish growth and reproduction. *
4. Behavior of freshwater crayfish. 
5. Chemical ecology of crayfish. 
6. Parasites, commensals, pathogens and diseases of crayfish. *
7. Environmental drivers for population success: population biology, population and community dynamics. *
8. Sampling techniques for crayfish. 
9. Laboratory methods for crayfish studies. 
10. The management of invasive crayfish. *

External links

Biology and Ecology of Crayfish (Publisher website)

Jackson, 2016

Jackson CJ. 2016. Characterization of locomotor response to psychostimulants in the parthenogenetic marbled crayfish (Procambarus fallax forma virginalis): a promising model for studying the epigenetics of addiction. Master’s thesis, Department of Biology, Bowling Green State University, Bowling Green, Ohio. https://etd.ohiolink.edu/!etd.send_file?accession=bgsu1467967151&disposition=inline

Abstract

Chapter I: Epigenetic regulation has been implicated as an important factor in understanding the molecular mechanisms of drug addiction. This is due to the life -long behavioral changes that commonly afflict addicted individuals long after drug exposure has been extinguished. Invertebrates, such as crayfish, offer excellent model systems to study these molecular mechanisms because they retain the ancestral neural reward circuit that is evolutionarily conserved across taxa, possess relatively few, large neurons, and have an accessible, modularly organized nervous system. The marbled crayfish (Procambarus fallax forma virginalis), in particular, has potential as a model for epigenetic studies because it is parthenogenetic, and thus all individuals are genetic clones. To provide the foundation of this model system for parsing the epigenetic mechanisms of drug addiction, here I characterize the locomotor response of juvenile P. f. f . virginalis exposed to the psychostimulant, d-amphetamine sulfate. Custom video-tracking software was used to record the movement patterns of juveniles exposed to water infused with varying concentrations of d-amphetamine sulfate. ANOVA demonstrated that crayfish locomotion was significantly impacted by drug concentration. These psychostimulant effects, along with the non-invasive mode of drug delivery, which avoids potential epigenetic changes resulting from the stress of direct injection into the hemolymph, set the stage for using P. f. f . virginalis as an animal model for epigenetic studies.

Chapter II: With the rising interest in using invertebrate models for behavioral epigenetic studies, and the tissue- specific nature of epigenetic changes, there is a need for effective methods of extracting genomic DNA from neural tissue. Invertebrates, such as crayfish, represent useful models in which to parse out the basic underlying epigenetic changes because of the relatively simplified anatomical structure of their nervous system. The parthenogenetic marbled crayfish (Procambarus fallax forma virginalis) offers a particularly elegant system because it reproduces asexually and produces large numbers of genetically identical offspring. However, the low DNA yield of fatty neural tissue combined with small sample size represent technical challenges in using invertebrate brains. The present study seeks to support the use of the marbled crayfish as a model for studying the mechanisms of behavioral epigenetics by providing an optimized method for genomic DNA extraction from invertebrate neural tissue.

Keywords: None provided.

Chucholl, 2016b

Chucholl C. 2016b. The bad and the super-bad: prioritising the threat of six invasive alien to three imperilled native crayfishes. Biological Invasions 18(7): 1967-1988. http://dx.doi.org/10.1007/s10530-016-1141-2

Abstract

Multiple species invasions and limited resources for management require prioritisation of deleterious effects of invaders on imperilled native species. This study prioritises the threat of six non-indigenous crayfish species (NICS) to three indigenous crayfish species (ICS) in southwestern Germany, a European region with high diversity of crayfish species and freshwater habitats. Using multivariate statistical analyses and niche-based species distribution models, the (1) contemporary and potential range overlap, (2) habitat overlap, and (3) rate of spread of the nine species were assessed. Predicted and contemporary range overlap with ICS was consistently the highest for the alien signal crayfish. Environmental niches of ICS tended to be associated with cooler temperatures (except for white-clawed crayfish), lower Human Influence Index, and higher terrain slope than that of alien Orconectes and Procambarus species, but were mostly similar to that of signal crayfish. Habitat overlap was found to be the highest between signal crayfish and ICS. In contrast to Orconectes and Procambarus species, signal crayfish also invade headwaters, where the most ICS populations occur. Range expansion during the past 15 years was the highest for signal crayfish, followed by Orconectes species. Because of the great potential to invade as-yet isolated refuge areas and spread at a high rate, signal crayfish is of the highest concern for conservation of ICS and should be primarily targeted by prevention and control measures. However, it merely represents the ‘worst of the worst’, since all NICS of North American origin are natural reservoirs of crayfish plague, a fatal disease of ICS.

Keywords: aquatic invaders • risk assessment • Crustacea • distribution models • habitat association

Lipták and colleagues, 2016

Lipták B, Mrugala A, Pekárik L, Mutkovic A, Grula D, Petrusek A, Kouba A. 2016. Expansion of the marbled crayfish in Slovakia: beginning of an invasion in the Danube catchment? Journal of Limnology 75(2): 305-312. http://dx.doi.org/10.4081/jlimnol.2016.1313

Abstract

The marbled crayfish, Procambarus fallax f. virginalis, is a taxon widely available in the aquarium pet trade, which has been introduced to open waters in several European countries and in Madagascar. Recent studies confirmed this parthenogenetically reproducing crayfish as a high-risk invasive species, and vector of the crayfish plague pathogen, Aphanomyces astaci. It has been first discovered in Slovakia in 2010, but the status of the local population was not studied since then. Due to enlarged sampling area around the first report and one locality, where we presupposed the crayfish occurrence, we identified new marbled crayfish populations. Here, we report presence of three newly established marbled crayfish populations in Slovakia. Two populations are located critically close to the Váh River, a major tributary of the Danube River; one of them being directly connected to the Váh River via a side channel during occasional floods. The third established marbled crayfish population was found at the mouth of a thermal stream flowing into the Nitra River, a tributary of the Váh River. In this stream, crayfish coexist with other exotic fish and gastropod species of aquarium origin. We presume that the reported localities may serve as a source for further expansion of the marbled crayfish in the mid-part of the Danube catchment. Floods, active dispersal (including overland), passive dispersal by zoochory or anthropogenic translocations are among the major drivers facilitating the marbled crayfish colonization. We have not detected the crayfish plague pathogen in any of the studied populations. However, if spreading further, the marbled crayfish will encounter established populations of crayfish plague carriers in the Danube River, in which case they may acquire the pathogen by horizontal transmission and contribute to spread of this disease to indigenous European crayfish species.

Keywords: aquarium pet trade • crayfish plague • freshwater crayfish • Procambarus fallax f. virginalis • species introductions

Chatila, 2016

Chatila Z. 2016. Lentiviral GFP transfection of the parthenogenic crayfish species, Procambarus fallax: a tool for examining the source of neural precursor cells in crayfish. Undergraduate honors thesis, Neuroscience, Wellesley College. http://repository.wellesley.edu/thesiscollection/345/

Abstract

The thesis is embargoed online until 22 April 2018. I am attempting to get a copy of the abstract to place here earlier than that.

Kouba and colleagues, 2016

Kouba A, Tíkal J, Císar P, Veselý L, Fort M, Príborský J, Patoka J, Buric M. 2016. The significance of droughts for hyporheic dwellers: evidence from freshwater crayfish. Scientific Reports 6: 26569. http://dx.doi.org/10.1038/srep26569

Abstract

Freshwater biodiversity is globally threatened by various factors while severe weather events like long-term droughts may be substantially devastating. In order to remain in contact with the water or stay in a sufficiently humid environment at drying localities, the ability to withstand desiccation by dwelling in the hyporheic zone, particularly through vertical burrowing is crucial. We assessed the ability of three European native and five non-native crayfish as models to survive and construct vertical burrows in a humid sandy-clayey substrate under a simulated one-week drought. Three native species (Astacus astacus, A. leptodactylus, and Austropotamobius torrentium) suffered extensive mortalities. Survival of non-native species was substantially higher while all specimens of Cherax destructor and Procambarus clarkii survived. The native species and Pacifastacus leniusculus exhibited no ability to construct vertical burrows. Procambarus fallax f. virginalis and P. clarkii constructed bigger and deeper burrows than C. destructor and Orconectes limosus. In the context of predicted weather fluctuations, the ability to withstand desiccation through constructing vertical burrows into the hyporheic zone under drought conditions might play a significant role in the success of particular crayfish species, as well as a wide range of further hyporheic-dwelling aquatic organisms in general.

Keywords: behavioural ecology • biodiversity • hydrology • limnology

Lőkkös and colleagues, 2016

Lőkkös A, Müller T, Kovács K, Várkonyi L, Specziár A, Martin P. 2016. The alien, parthenogenetic marbled crayfish (Decapoda: Cambaridae) is entering Kis-Balaton (Hungary), one of Europe’s most important wetland biotopes. Knowledge and Management of Aquatic Ecosystems 417: 16. http://dx.doi.org/10.1051/kmae/2016003

Abstract 

The marbled crayfish or Marmorkrebs, Procambarus fallax (Hagen, 1870) f. virginalis, a parthenogenetic freshwater crayfish belonging to the North American cambarids, was recorded in Hungary for the first time. Several specimens of this potentially invasive crayfish were caught at different locations in the thermal Lake Hévíz and its outflows in the western part of the country. Captured individuals covered a wide size range (5.5 to 50.5 mm carapace length) and one was carrying eggs and recently hatched offspring, which suggests that this organism has established a stable and self-sustaining population in the warm habitats of Lake Hévíz area. This finding is of great significance because these habitats belong to the catchment of the Danube River including Lake Balaton, and thus, a significant further spread of the marbled crayfish is likely to happen in Central Europe. Furthermore, the expansion of this crayfish already reached the Kis-Balaton, one of the landscape protection areas of the Balaton Uplands National Park, what could have currently yet unpredictable consequences for this unique wetland biotope.

Keywords: non-indigenous crayfish species • pet trade • illegal release • crayfish plague • thermal lake

Note: One of the latitude and longitude coordinates in Table 2 is incorrect. The coordinates for Lake Hévíz should be N 46° 47.252', E 17° 11.501'. The corresponding author confirmed this.

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.

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

Abstract

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

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]

Abstract

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.

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

Abstract

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.

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.

Reference

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

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.

References

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

Kasuya and Nagayama, 2016

Kasuya A, Nagayama T. 2016. Habituation of backward escape swimming in the marbled crayfish. Zoological Science 33(1): 6-12. http://dx.doi.org/10.2108/zs150099

Abstract

In the present study, we performed behavioral analyses of the habituation of backward escape swimming in the marbled crayfish, Procambarus fallax. Application of rapid mechanical stimulation to the rostrum elicited backward swimming following rapid abdominal flexion of crayfish. Response latency was very short—tens of msec—suggesting that backward swimming is mediated by MG neurons. When stimulation was repeated with 10 sec interstimulus intervals the MG-like tailflip did not occur, as the animals showed habituation. Retention of habituation was rather short, with most animals recovering from habituation within 10 min. Previous experience of habituation was remembered and animals habituated faster during a second series of experiments with similar repetitive stimuli. About half the number of stimulus trials was necessary to habituate in the second test compared to the first test. This promotion of habituation was observed in animals with delay periods of rest within 60 min following the first habituation. After 90 min of rest from the first habitation, animals showed a similar time course for the second habituation. With five stimuli at 15 min interval during 90 min of the rest, trained animals showed rapid habituation, indicating reinforcement of the memory of previous experiments. Crayfish also showed dishabituation when mechanical stimulation was applied to the tail following habituation.

Keywords: learning • memory • crayfish • tailflip • plasticity

The crayfish / crawfish / crawdad war II

A couple of years ago, some fun dialect maps were making the rounds on the Internet, which I blogged about because one of the questions was about what people call freshwater crustaceans that look like small lobsters.

Those maps were based on the Harvard dialect survey, which ended 2003. This is now being followed by the Cambridge dialect survey, which started 2007, and what people call Astacidea is again one of the questions.

The map is interesting to check out. I think “lobster” looks far more common in the map than in the data, probably because of the layering of the data points.

Interestingly, the gap in use between “crayfish” and “crawfish” widened between the Harvard and Cambridge surveys. But in both surveys, “crayfish” is more northeast, “crawdad” is midwestern, and “crawfish” is southern. I wonder how “fish” metamorphosed into “dad” in the central U.S.

Related posts

The crayfish / crawfish / crawdad war

External links

Harvard survey: Asticidea map
Cambridge survey: Astacidea map

Diversity

The world hotspot for crayfish species, by a long, long way, is the southeastern United States (map from Richman et al. 2015).

The southeastern U.S. is also notable for relatively large populations of African-Americans.

You might think that given the overlap in these two maps, that there would be expertise in the African-American community about crayfish. But I am struggling to think of any African-American scientist who has studied crayfish. Who am I missing?

This also points to crayfish being a great entry point to introduce African-Americans to topics like biology and conservation.

Reference

Richman, NI, Böhm, M, Adams, SB, Alvarez, F, Bergey, EA, Bunn, JJS, Burnham, Q, Cordeiro, J, Coughran, J, Crandall, KA, Dawkins, KL, Distefano, RJ, Doran, NE, Edsman, L, Eversole, AG, Füreder, L, Furse, JM, Gherardi, F, Hamr, P, Holdich, DM, Horwitz, P, Johnston, K, Jones, CM, Jones, JPG, Jones, RL, Jones, TG, Kawai, T, Lawler, S, López-Mejía, M, Miller, RM, Pedraza-Lara, C, Reynolds, JD, Richardson, AMM, Schultz, MB, Schuster, GA, Sibley, PJ, Souty-Grosset, C, Taylor, CA, Thoma, RF, Walls, J, Walsh, TS, Collen, B. 2015. Multiple drivers of decline in the global status of freshwater crayfish (Decapoda: Astacidea). Philosophical Transactions of the Royal Society of London B 370: 20140060.

External link

African-American History Month

Map of African-American distribution from here.

Marmorkrebs homepage moved

The Marmorkrebs.org home page has migrated over to a new institutional server. The old site will be up for a while until I get a redirect notice up, but it will eventually close as website support for my previous institution (The University of Texas-Pan American) transitions to my new one (The University of Texas Rio Grande Valley).

If you visit the site by a directly typing in the URL into a browser, you should see no difference.

If you  bookmarked the homepage, take a moment to check that it directs to the correct URL:

http://faculty.utrgv.edu/zen.faulkes/marmorkrebs/

You can let me know if there are any problems by emailing me at zen.faulkes@utrgv.edu.

Risk assessment, Irish style

In my tooling around the Internet for Marmorkrebs related research, I found this risk assessment for Marmorkrebs as a potential non-indigenous crayfish in Ireland. It seems to be an extremely thorough document.

Marmorkrebs are not the only crayfish assessed, either. Noble crayfish (Astacus astacus), Turkish crayfish (A. leptodactylus), spiny-cheek crayfish (Orconectes limosus), signal crayfish (Pacifastacus leniusculus), and the champion non-indigenous crayfish, the Louisiana red swamp crayfish (Procambarus clarkii) all get similarly extensive review.

External links

Non-native Species Risk Assessment for Ireland

Sell your Marmorkrebs, Tennesseans

A week ago, I reported stumbling upon  information indicating that Marmorkrebs had been designated “Class V Wildlife” (basically, zoos only) in Tennessee. I can now confirm that this is correct. This effectively means that keeping Marmorkrebs as pets is now illegal in Tennessee.

Trying to track this down required a little effort. As I mentioned before, my initial Google searches failed miserably. Twitter to the rescue!

The Tennessee Wildlife Resources Agency has a Twitter account. They replied to my tweet, and gave me a phone number to try. It took several tries over multiple days to get a person instead of a voice message. When I did get through, I got another phone number to try, but luckily, got an answer to on the first call. And the person I spoke to was able to confirm that Marmorkrebs was added to Tennessee’s list of Class V wildlife last October.

People have kept Marmorkrebs in Tennessee: I found some owners discussing their pets in a previous paper (Faulkes 2013; data here). But I wonder how someone who wants to be a responsible, law-abiding pet owner is supposed to learn about this new regulation. I specifically watch for news about Marmorkrebs like a hawk, and I missed this item for three months. Then it took me almost a week of phone tag to track down someone who could confirm it. The Tennessee officials I spoke to on the phone were super helpful, but still, I put in considerable effort to learn this information. Not everyone will have my obsessive motivation.

References

Faulkes Z. 2013. How much is that crayfish in the window? Online monitoring of Marmorkrebs, Procambarus fallax f. virginalis (Hagen, 1870) in the North American pet trade. Freshwater Crayfish 19(1): 39-44. http://dx.doi.org/10.5869/fc.2013.v19.039

Supplemental info: Faulkes Z. 2013. Online monitoring of Marmorkrebs in the North American pet trade. figshare. http://dx.doi.org/10.6084/m9.figshare.645344

Related posts


Owning Marmorkrebs in Tennessee might just be illegal now