Sanna and colleagues, 2021

Sanna D, Azzena I, Scarpa F, Cossu P, Pira A, Gagliardi F, Casu M. 2021. First record of the alien species Procambarus virginalis Lyko, 2017 in fresh waters of Sardinia and insight into its genetic variability. Life 11(7): 606. https://doi.org/10.3390/life11070606

 

Abstract

 

In the fresh waters of Sardinia (Italy), the non-indigenous crayfish species Procambarus clarkii has been reported from 2005, but, starting from 2019, there have been several reports of a new nonindigenous crayfish in southern and central areas of this Mediterranean island, and its morphology suggests that this species may be the marbled crayfish Procambarus virginalis. Forty-seven individuals of this putative species were analyzed, using the mitochondrial gene Cytochrome c Oxidase subunit I as molecular marker to identify this crayfish and investigate the level of genetic variability within the recently established population. Phylogenetic and phylogeographic analyses were carried out on a dataset including sequences from the Sardinian individuals and from all congenerics available in GenBank. Results showed that the new Sardinian crayfish belong to the species P. virginalis. All the sequences belonging to P. virginalis from European countries are identical, with only few exceptions found among Sardinian individuals. In conclusion, this paper highlights the occurrence of a new further alien species in the Sardinian fresh waters, which are already characterized by the high presence of non-indigenous species.

 

Keywords: alien species • invasive species • non-indigenous crayfish • biological invasion • marbled crayfish • Sardinian fresh waters • mtDNA

 

 

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.

 

 

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

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

 

Abstract

 

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.