Bohman and colleagues, 2013

Bohman P, Edsman L, Martin P, Scholtz G. 2013. The first Marmorkrebs (Decapoda: Astacida: Cambaridae) in Scandinavia. BioInvasions Records 2(3): 227–232. http://dx.doi.org/10.3391/bir.2013.2.3.09

Abstract

Invasive crayfish have attracted much attention by scientists and policy makers in Europe, partly due to their ability to transmit diseases to native crayfish species. In December 2012, 13 specimens of a new crayfish species were found in the River Märstaån in central Sweden. Mitochondrial DNA analyses identified them as Marmorkrebs Procambarus fallax f. virginalis. It is not known if Marmorkrebs can establish reproducing populations in Sweden, and knowledge of how different stressors negatively affect the eventual reproduction of Marmorkrebs is lacking. Since the parthenogenetic Marmorkrebs has potential to become an invasive species in Sweden and Scandinavia, it may pose a serious threat to native crayfish, fish and fisheries. Swedish authorities have produced an action plan with a national strategy in order to establish a system that manages the import, movement and release of alien species and genotypes. The River Märstaån leads to Lake Mälaren, without barriers, which enhances the risk that the crayfish will also invade the lake. Due to the potential threat of further spread, it is imperative to make an action plan with a risk assessment targeted specifically towards the Marmorkrebs in River Märstaån.

Keywords: Procambarus fallax f. virginalis • parthenogenetic • crayfish • disease • risk analysis • action plan

Plague poster

From Kärntner Institut für Seenforschung (roughly translated, the Carinthian Institute for Lake Research) comes this poster on whether Marmorkrebs can spread the dreaded crayfish plague (click to enlarge):

The short answer is yes, as predicted. Although they can carry it, there are still no reports of Marmorkrebs in the wild carrying crayfish plague that I know of.

This poster was presented at the 16th International Conference on Diseases of Fish and Shellfish. This meeting had a large symposium on crayfish plague.

External links

Kärntner Institut für Seenforschung
16th International Conference on Diseases of Fish and Shellfish

Turning the tide

Marmorkrebs are a concern as an emerging invasive crayfish, but in much of the world, they still have a long way to go before they catch up with other exotic crayfish. In North American, a lot of attention has revolved around the rusty crayfish, Orconectes rusticus.

This article describes an effort to control rusty crayfish in a semi-natural setting that seemed to have worked. The abstract reports that they reduced the number of crayfish by 99% of where they started. The paper goes on to look at what happens to the lake when the crayfish are gone. As I’ve often said to people, “A lake with crayfish looks completely different than one without crayfish,” and this research bears that out.

How did the team get this invasive crayfish under control? Trapping, and a lot of elbow grease (my emphasis).

Hansen thinks that, if the right agency or lake association had the time and money to pay someone to extensively trap crayfish, it could work. But, she cautions, it’s a lot of work. Her group needed eight summers of full-time trapping to finally get rusty crayfish numbers where they wanted them.

Reference

Hansen GJA, Hein CL, Roth BM, Vander Zanden MJ, Gaeta JW, Latzka AW, Carpenter SR. 2013. Food web consequences of long-term invasive crayfish control. Canadian Journal of Fisheries and Aquatic Sciences 70:1109-1122. http://dx.doi.org/10.1139/cjfas-2012-0460

External links

In whole-lake experiment, have invasive crayfish met their match?

Janský and Mutkovič, 2010

Janský V, Mutkovič A. 2010. Rak Procambarus sp. (Crustacea: Decapoda: Cambaridae) – prvý nález na slovensku. Acta Rerum Naturalium Musei Nationalis Slovaci 56: 64-67.

Abstract

Marbled crayfish – Procambarus sp. (Crustacea: Decapoda: Cambaridae) – first find in Slovakia. The species was found in gravelpit near-by the village Koplotovce, in May 2010. Distribution of this species in Europe and its risk for our nature is discused (sic).

Keywords: marbled crayfish • distribution • Slovakia

Note: Paper in Slovak.

Marmorkrebs found in Sweden, again

Apologies for being a bit behind the curve on this one, but I just saw the latest press release from back in July from the Swedish Agency for Marine and Water Management saying that Marmorkrebs had been found again this last summer, and in a different location that last autumn, and multiple individuals of different sizes.

This is not good news for Sweden, as it suggests Marmorkrebs are gaining a beachhead in that country.

External links

Nya fynd av misstänkt marmorkräfta har hittats i Västsverige
New Discoveries of Marbled Crayfish Cause Concern in Northern Europe (Note: English language press releases from this site do not appear to be archived as well as the Swedish language ones are.)

Picture from Swedish Agency for Marine and Water Management.

Quoth the crayfish, "Nevermore"

There are about eight native crayfish species in Russia, and those crayfish have made an impression on the vernacular. This expression means, "Never":

когда рак на горе свистнет (kogdá rak na goré svístnet) — “When the crawfish whistles on the mountain”.

For more ways of saying "Never," see here. It misses a favourite of mine, though. Apparently, in ancient Rome, an expression for "never" was, "When a mule foals."

External link

When Pigs Fly, Crayfish Whistle, and It Snows Red Snowflakes

Parthenogenesis primer

The Raptor Lab has a nice primer on parthenogenesis, although it focuses only on the phenomenon in pit vipers.

As if we required further proof life is weird, in walks parthenogenesis, an evolutionarily fascinating and frightening reproductive strategy, serving another round.