22 June 2018

Vogt, 2018c

Vogt G. 2018. Glair glands and spawning in unmated crayfish: a comparison between gonochoristic slough crayfish and parthenogenetic marbled crayfish. Invertebrate Zoology 15(2): 215–220. https://doi.org/10.15298/invertzool.15.2.02, http://kmkjournals.com/journals/Inv_Zool/IZ_Index_Volumes/IZ_15/IZ_15_2_215_220_Vogt

Abstract

In the period before spawning, freshwater crayfish females develop glair glands on the underside of the pleon. These glands produce the mucus for a gelatinous tentlike structure in which the eggs are fertilized and attached to the pleopods. Long-term observation of females of the sexually reproducing slough crayfish, Procambarus fallax, kept in captivity revealed that the glair glands developed in late winter and late summer of each year independently of the presence of males. In mated females, they secreted their contents shortly before spawning. In contrast, unmated females of slough crayfish did
neither empty their glair glands nor spawn. Their glands persisted for an unusually long period of time and disappeared only during the next moult. Apparently, slough crayfish females use information on sperm availability to either spawn or save the resources. Females of marbled crayfish, Procambarus virginalis, a parthenogenetic all-female descendant of slough crayfish, developed glair glands in approximately the same periods of the year but generally spawned despite of the lack of males. These findings suggest that in marbled crayfish glair secretion and spawning is decoupled from mating. Therefore, the species pair P. fallax and P. virginalis seems to be particularly suitable to investigate the regulation of spawning in freshwater crayfish.

Keywords: freshwater crayfish • glair gland • spawning • mating • Procambarus fallaxProcambarus virginalis


Zoo babies


Marbled crayfish are featured in this year’s Cincinnati Zoo’s Zoo Babies display! The Zoo’s website shows they are part of the display, but no more. I do complement their photographer for the particularly cute crayfish pic (above) on their site.

I reached out to the Zoo, and heard back from Mandy Pritchard, who is the “World of the Insect Team Leader” at the zoo. (Now there’s a great job title.) She was kind enough to send me a couple of pictures of the display:




There’s a very nice shirt available. Unfortunately, it’s doesn’t seem to be available in adult sizes.


Based on the description in the display, I think these are the sexual slough crayfish and not Marmorkrebs. But it’s fun to see crayfish on display nevertheless!

External links

Zoo Babies
The "Amazing" Marbled Crayfish - Youth Garments

19 June 2018

Herrmann and colleagues, 2018

Herrmann A, Schnabler A, Martens A. 2018. Phenology of overland dispersal in the invasive crayfish Faxonius immunis (Hagen) at the Upper Rhine River area. Knowledge and Management of Aquatic Ecosystems 419: 30. https://doi.org/10.1051/kmae/2018018

Abstract

The non-indigenous crayfish Faxonius immunis (Hagen) is the dominant crayfish species at the Upper Rhine River system since his detection in 1993. As an invasive alien species, it is one of the biggest threats to aquatic biodiversity in the area. By dispersing over land, the species has a high potential to colonize small ponds created for threatened amphibians and dragonflies. Shortly after invasion, the fast growing population of F. immunis is changing the habitat drastically. In June 2016, our team started a local information campaign including citizen science project where the local people south of Karlsruhe, Baden-Wuerttemberg, Germany, could contact us when they spot a crayfish migrating over land to assess the activity of overland dispersal on a regional scale. Until January 2018, we got a total of 98 responses. Thirty-nine include suitable information including 33 records of overland dispersal of F. immunis. The species was recorded on land throughout the year, except February and July. Additionally, single observations of overland dispersal of other invasive crayfish species, naming Procambarus clarkii (Girard), Pacifastacus leniusculus (Dana), Procambarus virginalis (Lyko) and Faxonius limosus (Rafinesque), were recorded.

Keywords: amphibian conservation • citizen science • management • biological invasions • non-indigenous species

08 June 2018

If this is 2018, this must be Estonia

Estonia has now become the...

Wait a second, I’ve lost count.

  1. Germany.
  2. Italy.
  3. Netherlands.
  4. Hungary.
  5. Croatia.
  6. Slovakia.
  7. Romania.
  8. Sweden.
  9. Ukraine.
  10. Czech Republic.
  11. ...
Eleventh European country where Marmorkrebs have been found in outdoors. This is according to a press release from the Estonian Research Council. The crayfish were collected last year, not recognized as Marmorkrebs until the end of the year, and a repeat visit at the end of May confirmed a population was there.

I have updated the map of Marmorkrebs introductions accordingly.

External links

The marbled crayfish have established themselves in Narva power plant