16 August 2018

Soes, 2016

Soes DM. 2016. Onderzoek voorkomen marmerkreeft in Middelburg. Rapportnummer 16‐250. Bureau Waardenburg, Culemborg. https://doi.org/10.13140/RG.2.2.10943.82081


De marmerkreeft is een in Nederland exotische rivierkreeft die valt onder de recent inwerking getreden Europese exotenverordening (EU 1143/2014). Van de marmerkreeft zijn uit Nederland tot op heden geen populaties bekend (Koese & Soes, 2011; D.M. Soes eigen informatie). Voor de marmerkreeft is het dan ook van belang nieuwe vestigingen snel te signaleren zodat eventueel maatregelen kunnen worden genomen die verdere verspreiding tegengaan of zelfs eliminatie mogelijk maken.

In 2014 en 2015 zijn in het westen van Middelburg (omgeving Hugo de Grootlaan) twee vondsten van mogelijke marmerkreeften gedaan. Eén waarneming betrof een dood exemplaar in een brandgang. Het tweede exemplaar werd levend aangetroffen in een tuinvijver. Verder is er nog een ongedateerde waarneming van een levende kreeft in dezelfde brandgang. Deze informatie was voor de NVWA aanleiding nader onderzoek uit te voeren.

In onderhavig rapportage wordt beschreven:
  1. de definitieve determinatie van de gevonden kreeften;
  2. een inventarisatie naar het eventueel voorkomen van de soort in de directe omgeving van de genoemde vondsten;
  3. de kansen op verspreiding indien zij in het westen van Middelburg daadwerkelijk zou voorkomen.
Keywords: None provided.

(English translation with Google Translate and some guesswork)

The marbled crayfish is a exotic crayfish in the Netherlands that falls under the recent the European Exotics Regulation (EU 1143/2014) came into effect. There are no populations known to date from the Netherlands (Koese & Soes, 2011; D.M. Soes, unpublished). It is therefore important for the early detection of marbled crayfish in new river branches quickly so that possible measures can be taken to prevent further dissemination or even enable elimination.

In 2014 and 2015 in the west of Middelburg (near Hugo de Grootlaan), two possible marbled crayfish were found. One observation was one dead copy in a firebreak. The second copy was found alive in a garden pond. There is also an undated observation of a living lobster in the same firebreak. This information was further explained by the NVWA conduct research.

This report describes:
1. the definitive determination of the crayfish found;
2. an inventory of the possible occurrence of the species in the direct environment of the findings;
3. the chances of spreading if they are in the west of Middelburg.

14 August 2018

Marenkov and colleagues, 2018

Marenkov O, Prychepa M, Kovalchuk J. 2018. The influence of heavy metal ions on the viability and metabolic enzyme activity of the marbled crayfish Procambarus virginalis (Lyko, 2017). International Letters of Natural Sciences 70: 11-23. https://doi.org/10.18052/www.scipress.com/ILNS.70.11


The article shows the results of studies on the influence of heavy metal ions (manganese, nickel, lead) on the viability and metabolic enzyme activity of marbled crayfish Procambarus virginalis (Lyko, 2017) (Decapoda). Due to the fact that marbled crayfish got into the reservoirs of the Dnipropetrovsk region in 2015, it was necessary to study the possibilities of its adaptation to environmental factors of reservoirs for further prediction of its distribution or even acclimatization under conditions of toxicological contamination of the ponds of the steppe Prydniprovya. In the
experiment with marbled crayfish, chronic effects of various concentrations of heavy metal ions on the physiological state and enzyme activity were investigated. The obtained results showed that
among the investigated heavy metals nickel ions influenced the weight indexes and mortality of crustaceans the most negatively. According to the results of the research, significant changes were
noted in the individual biochemical parameters of marbled crayfish under the influence of manganese, lead and nickel ions. The most significant changes in the activity of lactate dehydrogenase were detected in muscle tissues affected by manganese and nickel ions. A significant decrease in the activity of succinate dehydrogenase in muscle of marbled crayfish was determined after the action of heavy metal ions. Investigation of changes in the activity of alkaline phosphatase under the influence of the ions of manganese, lead and nickel has its own characteristics, which indicates certain violations in the tissues of cell membranes. Changes in the activity of enzymes were also reflected in the overall protein content. In conclusion, changes in these parameters may indicate a rapid biochemical response of crustaceans to the toxic effects of heavy metals.

Keywords: manganese • nickel • lead • crustaceans • Procambarus virginalis • succinate • dehydrogenase • lactate dehydrogenase • alkaline phosphatase

04 August 2018

"Say my name, say my name": The Guardian podcast

Marmorkrebs make an appearance in the Guardian's Science Weekly podcast as part of a discussion about naming species. If you're super directed, the marbled crayfish discussion with Tim Cockerill starts about 7 minutes in (07:20, to be exact).

This podcast raises a question for me, though. What is the preferred pronunciation of “slough”? As in Procambarus fallax, the slough crayfish? The podcast presenter, Graihagh Jackson, has it rhyme with “cow.” I’ve always pronounced with to rhyme with “you.” As this post notes, words ending in "-ough" have a bewildering number of sounds.

External links

Tricky taxonomy: the problems with naming new species

31 July 2018

The Great Lakes least wanted

The Michigan Sea Grant has spearheaded a “#CrayWeek” campaign for the second year in a row! Of course I’m participating.

One of the piece of information that Michigan Sea Grant tweeted out was that Marmorkrebs have found themselves on another invasive species watch list, this one for the Canadian / American Great Lakes and Saint Lawrence River.

On May 4, 2018, the Great Lakes St. Lawrence Governors & Premiers announced five additions to the list of “least wanted” aquatic invasive species. In 2013, the Governors and Premiers released the first list of 16 “least wanted” aquatic invasive species (AIS) that present a serious threat to the Great Lakes St. Lawrence Basin. Since then, the region’s eight states and two provinces have taken more than 40 actions to prohibit or restrict these high-risk species, including the Asian carp. The new “least wanted” AIS include:
  • Tench Tinca tinca
  • Marmorkreb (sic) (marbled crayfish) Procambarus fallax forma virginalis
  • New Zealand mud snail Potamopyrgus antipodarum
  • European frogbit Hydrocharis morsus-ranae
  • Yellow floating heart Nymphoides peltata
State and provincial AIS and fisheries experts, in conjunction with leading regional researchers, identified these five AIS as posing a high risk of invasion or spread within the region. The Governors and Premiers will take aggressive action and work with regional partners to prevent the spread of these aquatic invaders.

What’s not clear to me from this statment is what action has been, or might be, taken to try to curb the spread of any of these species. A recent paper I co-authored pointed out (Patoka et al. 2018), the track record of legislation on curbing the movement of aquarium pets is... not great.

External links

Great Lakes St. Lawrence Governors & Premiers Add Five “Least Wanted” AIS


Patoka J, Magalhães ALB, Kouba A, Faulkes Z, Jerikho R, Vitule JRS. 2018. Invasive aquatic pets: Failed policies increase risks of harmful invasions. Biodiversity and Conservation 27(11): 3037-3046. https://doi.org/10.1007/s10531-018-1581-3

26 July 2018

Le Page, 2018

Le Page M. 2018. Crayfish clone army on the loose. New Scientist 239(3185): 16. https://doi.org/10.1016/S0262-4079(18)31193-X


Without abstract. First paragraph:

Sometime before 1995, a container of freshwater crayfish from Florida got too hot or too cold en route to a pet shop in Germany. The shock disrupted the development of an egg being carried by one of the females, creating an army of clones that are invading rivers and lakes in continental Europe, Madagascar and Japan.

Keywords: None provided.

Notes: If you click to enlarge the cover of this issue, the cover includes “Clone crayfish” in the bottom left. This article was published online with the title, “Freak accident created a massive army of super-fertile clones.”

14 July 2018

Nischik and Krieger, 2018

Nischik ES, Krieger J. 2018. Evaluation of standard imaging techniques and volumetric preservation of nervous tissue in genetically identical offspring of the crayfish Procambarus fallax cf. virginalis (Marmorkrebs). PeerJ 6: e5181. https://doi.org/10.7717/peerj.5181


In the field of comparative neuroanatomy, a meaningful interspecific comparison demands quantitative data referring to method-specific artifacts. For evaluating the potential of state-of-the-art imaging techniques in arthropod neuroanatomy, micro-computed X-ray microscopy (μCT) and two different approaches using confocal laser-scanning microscopy (cLSM) were applied to obtain volumetric data of the brain and selected neuropils in Procambarus fallax forma virginalis (Crustacea, Malacostraca, Decapoda). The marbled crayfish P. fallax cf. virginalis features a parthogenetic reproduction generating genetically identical offspring from unfertilized eggs. Therefore, the studied organism provides ideal conditions for the comparative analysis of neuroanatomical imaging techniques and the effect of preceding sample preparations of nervous tissue. We found that wet scanning of whole animals conducted with μCT turned out to be the least disruptive method. However, in an additional experiment it was discovered that fixation in Bouin’s solution, required for μCT scans, resulted in an average tissue shrinkage of 24% compared to freshly dissected and unfixed brains. The complete sample preparation using fixation in half-strength Karnovsky’s solution of dissected brains led to an additional volume decrease of 12.5%, whereas the preparation using zinc-formaldehyde as fixative resulted in a shrinkage of 5% in comparison to the volumes obtained by μCT. By minimizing individual variability, at least for aquatic arthropods, this pioneer study aims for the inference of method-based conversion factors in the future, providing a valuable tool for reducing quantitative neuroanatomical data already published to a common denominator. However, volumetric deviations could be shown for all experimental protocols due to methodological noise and/or phenotypic plasticity among genetically identical individuals. MicroCT using undried tissue is an appropriate non-disruptive technique for allometry of arthropod brains since spatial organ relationships are conserved and tissue shrinkage is minimized. Collecting tissue-based shrinkage factors according to specific sample preparations might allow a better comparability of volumetric data from the literature, even if another technique was applied.

Keywords: μCT • confocal laser scanning microscopy • nervous system • volumetry • Marmorkrebs • phenotypic plasticity

10 July 2018

Conference hashtag #IAA22

I was unable to go to the International Association of Astacology meeting this year, but have been following along on Twitter, using the #IAA22 hashtag. Those following from home have been fortunate to have Maggie Watson sketchnoting many of the presentations, and I can’t resist sharing her Marmorkrebs notes here and here)!

If you go to a conference, tweet about it. More people want to attend than can attend.