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.