16 January 2018

Kubiak and Pellett, 2018

Kubiak M, Pellett S. 2018. Invasive alien species legislation: a veterinary perspective. Companion Animal 23(1): 44-48. https://doi.org/10.12968/coan.2018.23.1.44


The European Union (EU) Invasive Alien Species (IAS) Regulation (1143/2014) restricts keeping of named species, in order to preserve native biodiversity. As some of these species are currently kept by private exotic animal keepers, zoological collections and animal encounter businesses, it is important for veterinary surgeons to be aware of the restrictions. As of August 2017, new species have been added to the legislation; this article reviews the previous situation and includes the updated information.

Keywords: invasive alien species • legislation • Tamias sibiricusProcyon lotorTrachemys scriptaNasua nasua

Maguire and colleagues, 2018

Maguire I, Klobučar G, Žganec K, Jelić M, Lucić A, Hudina S. 2018. Recent changes in distribution pattern of freshwater crayfish in Croatia − threats and perspectives. Knowledge and Management of Aquatic Ecosystems 419: 2. https://doi.org/10.1051/kmae/2017053


Analysis of Croatian freshwater crayfish populations, aiming to gather new distributional data and complement previous surveys (2005–2011), was performed during 2014–2016, within the frame of Natura 2000 Integration Project. The research included different waterbodies across the whole of Croatia, harbouring both indigenous and non-indigenous crayfish species (ICS and NICS, respectively). Field work was conducted in 117 grid squares with dimensions 10 × 10 km, and up to four waterbodies were surveyed per grid square, making a total of 450 studied sites. Out of those, crayfish were not recorded in 368 sites. In the sites with crayfish presence (i.e., 82), the most frequently observed ICS was Astacus astacus (registered in 33 sites) followed by Austropotamobius pallipes (16 sites), Austropotamobius torrentium (12 sites), and Astacus leptodactylus (5 sites). Concerning NICS, the majority of records were for Orconectes limosus (13 sites), followed by Pacifastacus leniusculus (2 sites), whereas Procambarus fallax f. virginalis was registered in only one locality. Comparisons of obtained data with those from previous surveys showed that NICS are progressively spreading and displacing ICS, as recorded for A. leptodactylus that was almost completely displaced by O. limosus in waterbodies of the east Croatia. Existing ICS populations are under growing anthropogenic preassure, frequently fragmented and isolated. Moreover, this survey showed that in the last decade 55% of A. astacus and 67% of A. pallipes populations disappeared mainly as a consequence of anthropogenic influence onto their habitats. Further monitoring and conservation actions for ICS should be urgently applied to mitigate negative impacts of both NICS and anthropogenic influence.

Keywords: noble crayfish • narrow-clawed crayfish • stone crayfish • white-clawed crayfish • non-indigenous crayfish species

31 December 2017

2017 was the second best year ever for Marmorkrebs research

This is an annual tradition here on the Marmorkrebs blog! It’s fun to make this graph longer and longer every year...

In terms of straight journal articles, 2017 was tied with 2016: fifteen each. There was just no book dropping a set of chapters to lift the total like last year

There were some significant papers this year. There was a proposal to elevate Marmorkrebs to its own species. Part of this included deposition of reference specimens in a museum, which should be a useful long-term resource, regardless of whether the community moves to the proposed new species name, Procambarus virginalis.

The number of introduced populations continued to increase, with more reports in the scientific literature of European locations and newspaper reports of more discoveries in Japan.

And perhaps most excitingly for next year, there were several doctoral theses that will hopefully become publications in the near future. Maybe even 2018! (One paper, by Císař and others, has already been published with a 2018 publication date.)

The overall trendline still shows no sign 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
2016 was the best year ever for Marmorkrebs research

29 December 2017

Císař and colleagues, 2018

Císař P, Saberioon M, Kozák P, Pautsina A. 2018. Fully contactless system for crayfish heartbeat monitoring: undisturbed crayfish as bio-indicator. Sensors and Actuators B: Chemical 255(1): 29-34. https://doi.org/10.1016/j.snb.2017.07.160


The crayfish is widely accepted as very sensitive and fast bio-indicator of changes in water quality. Studies based on heart beat analysis demonstrated the potential of using crayfish as a detector of pollutants consequently several computer-aided systems were developed to use this mechanism. The main complication with applying such a system is the necessity of using metal wires or optical fibres to transmit the signal from sensor which is placed on back of the crayfish to the processing hardware; these attachments restrict system design to one crayfish in one aquarium. We introduced an original system for crayfish heart beat monitoring based on completely non-invasive/contactless hardware. The system can determine crayfish heart beat frequency using only the combination of near infra-red (NIR) illuminator and sensitive camera. The heart rate is the only parameter needed in most of the studies using crayfish as a bio-indicator. We developed the system which needs no attachment, so more crayfish in one aquarium can be monitored simultaneously and it provides accurate information on heart rate and crayfish need no adaptation to the system. It can be used as equivalent to existing systems to simplify the crayfish studies.

Keywords: crayfish • bio-indicator • heart rate • contactless • non-invasive • water quality

27 December 2017

Veselý and colleagues, 2017

Veselý L, Boukal DS, Buřič M, Kozák P, Kouba A, Sentis A. 2017. Effects of prey density, temperature and predator diversity on nonconsumptive predator-driven mortality in a freshwater food web. Scientific Reports 7: 18075. https://doi.org/10.1038/s41598-017-17998-4


Nonconsumptive predator-driven mortality (NCM), defined as prey mortality due to predation that does not result in prey consumption, is an underestimated component of predator-prey interactions with possible implications for population dynamics and ecosystem functioning. However, the biotic and abiotic factors influencing this mortality component remain largely unexplored, leaving a gap in our understanding of the impacts of environmental change on ecological communities. We investigated the effects of temperature, prey density, and predator diversity and density on NCM in an aquatic food web module composed of dragonfly larvae (Aeshna cyanea) and marbled crayfish (Procambarus fallax f. virginalis) preying on common carp (Cyprinus carpio) fry. We found that NCM increased with prey density and depended on the functional diversity and density of the predator community. Warming significantly reduced NCM only in the dragonfly larvae but the magnitude depended on dragonfly larvae density. Our results indicate that energy transfer across trophic levels is more efficient due to lower NCM in functionally diverse predator communities, at lower resource densities and at higher temperatures. This suggests that environmental changes such as climate warming and reduced resource availability could increase the efficiency of energy transfer in food webs only if functionally diverse predator communities are conserved.

Keywords: None provided.

Levy and colleagues, 2017

Levy T, Rosen O, Simons O, Alkalay AS, Sagi A. 2017. The gene encoding the insulin-like androgenic gland hormone in an all-female parthenogenetic crayfish. PLOS ONE 12(12): e0189982. https://doi.org/10.1371/journal.pone.0189982


Male sexual differentiation in crustaceans is controlled by the androgenic gland (AG), a unique male endocrine organ that, in decapods, is located at the base of the 5th pereiopod. In these animals, the insulin-like androgenic gland hormone (IAG) is the major factor secreted from the AG to induce masculinization and maintain male characteristics. It has, however, recently been proposed that this hormone also plays a role in growth and ovarian development in females. In this study, we tested such a possibility by searching for the IAG gene in the marbled crayfish, a parthenogenetic animal that reproduces asexually to form an all-female genetic clone. Based on the phylogenetic relationship between the marbled crayfish and Procambarus fallax, a gonochoristic species of the same North American Cambaridae family, we searched for the IAG gene in the marbled crayfish and then fully sequenced it. The open reading frame of the gene was found to be completely identical in the two species, and their introns shared over 94% identity. It was also found that, in addition to its expression at the base of the 5th pereiopod and in the testes of male P. fallax crayfish, IAG was expressed in the muscle tissue of P. fallax males and females and even of the parthenogenetic marbled crayfish. These findings provide new insight into possible functions of IAG, in addition to its role as a masculinization-inducing factor, and also constitute the basis for a discussion of the evolutionary relationship between the above two species.

Keywords: None provided.

16 December 2017

22nd International Symposium on Freshwater Crayfish announcement

The eastern US is the plce to be for crustacean research next year. It will not only host the International Crustacean Congress in Washington, it will be hosting the next Astacology meeting in Pittsburgh. Mark your calendars for 9-13 July 2018!

External links

IAA22 meeting announcement