19 June 2021

Fun for people of all ages! Marmorkrebs colouring

I stumbled across a page with a coloring book style blank illustration of Marmorkrebs! While the page says it’s for kids, there’sa a lot of fine detail that makes me think some young ones may find it a little on the high end of the difficulty scale.


Black and white outline of crayfish for colouring.


The shape of the claws looks much more like Louisiana red swamp crayfish than Marmorkrebs, though.

01 June 2021

Muuga 2021

Muuga J-M. 2021. Effects of temperature on marbled crayfish (Procambarus virginalis, Lyko 2017) invasion ecology. Master’s thesis, Hydrobiology and Fishery, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences. http://hdl.handle.net/10492/6695




Biological invasions are crucial issues worldwide and marbled crayfish (Procambarus virginalis, Lyko 2017) is one of the examples of freshwater invaders spreading across Europe and beyond. Marbled crayfish has high growth rate and reproduces via parthenogenesis, making it unique among other decapod species. Even though it is a warm water species, they can resist colder temperatures and are highly adaptable. Furthermore, it is also a vector for Aphanomyces astaci, causing crayfish plague. Due to its high adaptability, fast growth and reproduction, since one individual is enough to start a new population, it is important to understand its invasion ecology in order to implement better management plan in the new invaded ecosystems. In this thesis the main goal was to assess whether the temperature is the main factor of marbled crayfish establishment and distribution in the artificially warm outflow channel of Balti Power Plant in Narva. We hypothesised to find temperature gradient along the channel which reflects marbled crayfish distribution and trophic niche. We analysed marbled crayfish and their potential food sources for stable carbon (13C) and nitrogen (15N) isotopes to assess its trophic niche. Temperature data did not show the gradient in the channel, however the channel was significantly warmer than Narva Reservoir. Stable isotope results showed change in marbled crayfish diets and trophic niche along the channel and between seasons, indicating a shift from enriched carbon to depleted carbon values from head to mouth of the channel and a shift from high to lower trophic level from spring and summer to autumn. Moreover, results showed diets being similar in head and middle of channel where crayfish mostly rely on macroinvertebrates and macrophytes, while in the mouth of the channel diet seems to shift more towards periphyton. Diet also changed from protein-rich in spring to vegetation-based diet in autumn. Based on the results, temperature had important role in the marbled crayfish establishment in the invaded channel, however the distribution of its population might have been affected by ecological aspects rather than temperature, like better food availability in the head of the channel.


Keywords: invasive species • trophic niche • temperature • Procambarus virginalis • stable isotopes

Note: Embargoed until 3 September 2021.

27 May 2021

Marmorkrebs in Taipei update

Last November, I reported on Marmorkrebs were found in Taipei, but they seemed to be confined to a single park pond. A brief mention in a new story suggests there is a second location that has become home to a population of Marmorkrebs. 

The firefly restoration ecological pond in Taipei’s Daan Forest Park is being invaded by an exotic species, the many-rayed sailfin sucker catfish, while Neihu District’s (內湖) Bihu Park is being invaded by the invasive marbled crayfish, causing ecological balance issues, the office said.


Emphasis added.


Marmorkrebs were previously reported in Daan Forest Park, so it is not entirely clear to me if Marmorkrebs are in two parks, or id the reporter inadvertently switched the two locations. I have updated the map of Marmorkrebs introductions with the second Taipei location, but noted the uncertainty.


External links

Taipei to issue fines for feeding wildlife in parks


Related posts


Marmorkrebs’ second Asian invasion

14 May 2021

Roje and colleagues 2021

Roje S, Richter L, Worischka S, Let M, Veselý L, Buřič M. 2021. Round goby versus marbled crayfish: Alien invasive predators and competitors. Knowledge and Management of Aquatic Ecosystems 422: 18. https://doi.org/10.1051/kmae/2021019



Aquatic biodiversity is threatened by spread of invasive alien species. Round goby Neogobius melanostomus is an invasive fish in large European rivers as well as in coastal waters near their mouths and marbled crayfish Procambarus virginalis is a highly invasive crustacean. Both are small, bottom-dwelling species occupying similar habitat and shelters and utilizing similar food sources. We hypothesized that goby presents a threat to both native and non-native astacofauna in invaded ecosystems. We tested this through laboratory experiments designed to determine aggressiveness and competitiveness of goby against marbled crayfish as a model for other North American cambarid crayfish, assessing goby prey size selection and competition with marbled crayfish for space and shelter. Gobies showed high aggressiveness and dominance over the crayfish. Goby predation on juvenile crayfish was limited by mouth gape size. In goby/crayfish pairs of similar weight, gobies were more aggressive, although each affected the behavior of the other.


Keywords: Biological invasion • freshwater • predation • shelter competition • species interaction


Open access


11 May 2021

Kouba and colleagues 2021

Biology journal logo

Kouba A, Lipták B, Kubec J, Bláha M, Veselý L, Haubrock PJ, Oficialdegui FJ, Niksirat H, Patoka J, Buřič M. 2021. Survival, growth, and reproduction: Comparison of marbled crayfish with four prominent crayfish invaders. Biology 10(5): 422. https://www.mdpi.com/2079-7737/10/5/422



Biological invasions are increasingly recognized ecological and economic threats to biodiversity and are projected to increase in the future. Introduced freshwater crayfish in particular are protruding invaders, exerting tremendous impacts on native biodiversity and ecosystem functioning, as exemplified by the North American spiny-cheek, signal and red swamp crayfish as well as the Australian common yabby. The marbled crayfish is among the most outstanding freshwater crayfish invaders due to its parthenogenetic reproduction combined with early maturation and high fecundity. As their introduced ranges expand, their sympatric populations become more frequent. The question of which species and under what circumstances will dominate in their introduced communities is of great interest to biodiversity conservation as it can offer valuable insights for understanding and prioritization of management efforts. In order to examine which of the aforementioned species may be more successful as an invader, we conducted a set of independent trials evaluating survival, growth, claw injury, and reproduction using single-species stocks (intraspecific interactions) and mixed stocks (interspecific interactions) of marbled crayfish vs. other crayfish invaders since the onset of exogenous feeding. In both single and mixed stocks, red swamp crayfish and yabby grew faster than marbled crayfish, while marbled crayfish were superior to both spiny-cheek and signal crayfish in terms of growth. With the exception of signal crayfish, the faster-growing species consistently reached a higher survival rate. The faster-growing species tended to negatively impair smaller counterparts by greater claw injury, delayed maturation, and reduced fecundity. Only marbled crayfish laid eggs as early as 14 weeks in this study, which is earlier than previously reported in the literature. Thus, the success of marbled crayfish among invasive crayfish is significantly driven by relatively fast growth as well as an early and frequent reproduction. These results shed light on how interactions between invasive populations can unfold when their expansion ranges overlap in the wild, thereby contributing to the knowledge base on the complex population dynamics between existing and emerging invasive species. 

Keywords: Biological invasion • pet trade • animal release • species interactions • sympatry

Open access

30 April 2021

Zoobabies, 2021 edition

The Cincinatti Enquirer answers a question I’ve been wondering for a while. 


Some years ago, I noted the Cincinatti Zoo had a display of “Marbled crayfish” and listed them as Procambarus fallax. The zoo’s description mentioned nothing about asexual reproduction, so I thought they were slough crayfish from Florida or Georgia.

But a new article about the zoo says:


This baby marbled crayfish resembles a small lobster, but it will only grow to 2 to 3 inches long. All marbled crayfish are women. They don't need a partner to reproduce.

Marmorkrebs they are, then! Which makes me wonder why their reproduction wasn’t mentioned on the display.

Related posts


Zoo babies


External links


Up close with the Cincinnati Zoo's most adorable ambassadors

29 April 2021

International Conference on Aquatic Invasive Species 2022

International Conference on Aquatic Invasive Species logo

The date for the next conference on aquatic invasive species will be 18-22 April 2022 in Belgium. It will be a mix of in person and online and the focus will be on climate change. But I’m sure there will be some crayfish content!


It must be challenging to plan conferences, since COVID-19 is still out of control in some regions but maybe coming under control with vaccination and we really don’t know what will happen.

External links


22nd International Conference on Aquatic Invasive Species