Göpel and Burggren 2024

Göpel T, Burggren WW. 2024. Temperature and hypoxia trigger developmental phenotypic plasticity of cardiorespiratory physiology and growth in the parthenogenetic marbled crayfish, Procambarus virginalis Lyko, 2017. Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 288: 111562. https://doi.org/10.1016/j.cbpa.2023.111562

Abstract

Attempting to differentiate phenotypic variation caused by environmentally-induced alterations in gene expression from that caused by actual allelic differences can be experimentally difficult. Environmental variables must be carefully controlled and then interindividual genetic differences ruled out as sources of phenotypic variation. We investigated phenotypic variability of cardiorespiratory physiology as well as biometric traits in the parthenogenetically-reproducing marbled crayfish Procambarus virginalis Lyko, 2017, all offspring being genetically identical clones. Populations of P. virginalis were reared from eggs tank-bred at four different temperatures (16, 19, 22 and 25 °C) or two different oxygen levels (9.5 and 20 kPa). Then, at Stage 3 and 4 juvenile stages, physiological (heart rate, oxygen consumption) and morphological (carapace length, body mass) variables were measured. Heart rate and oxygen consumption measured at 23 °C showed only small effects of rearing temperature in Stage 3 juveniles, with larger effects evident in older, Stage 4 juveniles. Additionally, coefficients of variation were calculated to compare our data to previously published data on P. virginalis as well as sexually-reproducing crayfish. Comparison revealed that carapace length, body mass and heart rate (but not oxygen consumption) indeed showed lower, yet notable coefficients of variation in clonal crayfish. Yet, despite being genetically identical, significant variation in their morphology and physiology in response to different rearing conditions nonetheless occurred in marbled crayfish. This suggests that epigenetically induced phenotypic variation might play a significant role in asexual but also sexually reproducing species.

RIP Günter Vogt

I recently learned from the CRUST-L mailing list that Günter Vogt in this last June. He was one of the earliest and most prolific authors studying Marmorkrebs and a wonderful booster of this blogging project. I was lucky enough to meet him at SICB some years ago and had a wonderful talk. He will be missed.

Hamr 2023

Hamr P. 2023. First record of the marbled crayfish in Canada/North America. Crayfish News 45(1-2): 1, 3. https://www.astacology.org/docs/cn/CrayfishNews_45(1-2)_hr.pdf (Direct link to PDF)

Abstract

Without abstract. First paragraph: 

 

Suspected marbled crayfish (Procambarus virginalis) were first reported in Southern Ontario in October 2021. The reports came from a Burlington City Park and were made by a naturalist (Ms. N. Bucik) as well as park staff who observed and photographed individual crayfish walking on a nature path as well as on a nearby football (soccer) pitch. All the reports were made near three stormwater ponds in the park where it was suspected the crayfish came from. (The identity of the crayfish was subsequently confirmed by EU crayfish experts when I showed the photos at IAA 23 in the Czech Republic in July 2022). 

Keywords: None provided.

Vogt, 2023

Vogt G. 2023. Phenotypic plasticity in the monoclonal marbled crayfish is associated with very low genetic diversity but pronounced epigenetic diversity. Current Zoology 69(4): 426-441. https://doi.org/10.1093/cz/zoac094

Abstract

Clonal organisms are particularly useful to investigate the contribution of epigenetics to phenotypic plasticity, because confounding effects of genetic variation are negligible. In the last decade, the apomictic parthenogenetic marbled crayfish, Procambarus virginalis, has been developed as a model to investigate the relationships between phenotypic plasticity and genetic and epigenetic diversity in detail. This crayfish originated about 30 years ago by autotriploidy from a single slough crayfish Procambarus fallax. As the result of human releases and active spreading, marbled crayfish has established numerous populations in very diverse habitats in 22 countries from the tropics to cold temperate regions. Studies in the laboratory and field revealed considerable plasticity in coloration, spination, morphometric parameters, growth, food preference, population structure, trophic position and niche width. Illumina and PacBio whole-genome sequencing of marbled crayfish from 19 populations in Europe and Madagascar demonstrated extremely low genetic diversity within and among populations, indicating that the observed phenotypic diversity and ability to live in strikingly different environments is not due to adaptation by selection on genetic variation. In contrast, considerable differences were found between populations in the DNA methylation patterns of hundreds of genes, suggesting that the environmentally induced phenotypic plasticity may be mediated by epigenetic mechanisms and corresponding changes in gene expression. Specific DNA methylation fingerprints persisted in local populations over successive years, but there is presently no information as to whether these epigenetic signatures are inherited or established anew in each generation and whether the recorded phenotypic plasticity is adaptive or non-adaptive.

Keywords: phenotypic plasticity • environmental adaptation • whole genome sequencing •
epigenetics • DNA methylation • marbled crayfish

Carneiro and colleagues 2023

Carneiro VC, Galil B, Lyko F. A voyage into the Levant: the first record of a marbled crayfish Procambarus virginalis (Lyko, 2017) population in Israel. BioInvasion Records 12(3): 829-836. https://doi.org/10.3391/bir.2023.12.3.18

Abstract 

The marbled crayfish, Procambarus virginalis (Lyko, 2017) is a novel parthenogenetic freshwater species that has rapidly colonized diverse habitats in Europe and Madagascar. Here we describe the first wild population of marbled crayfish in the Middle East. Numerous specimens, including gravid females, were collected in the waters of a spring on Mt. Carmel, Israel. The results from phenotypic, morphometric and genetic analyses showed the close relationship with other known populations, consistent with the clonal structure of the global marbled crayfish population. Our findings represent a considerable expansion of the known distribution range and further illustrate the role of anthropogenic activities in the dispersal of marbled crayfish.

Keywords: invasive species • freshwater crayfish • freshwater ecology • anthropogenic dispersal

Faiad and colleagues, 2023

Faiad SM, Williams MA, Goodman M, Sokolow S, Olden JD, Mitchell K, Andriantsoa R, Jones JPG, Andriamaro L, Ravoniarimbinina P, Rasamy J, Ravelomanana T, Ravelotafita S, Ravo R, Rabinowitz P, De Leo GA, Wood CL. 2023. Temperature affects predation of schistosome-competent snails by a novel invader, the marbled crayfish Procambarus virginalis. PLOS ONE 18(9): e0290615. https://doi.org/10.1371/journal.pone.0290615

 Abstract

The human burden of environmentally transmitted infectious diseases can depend strongly on ecological factors, including the presence or absence of natural enemies. The marbled crayfish (Procambarus virginalis) is a novel invasive species that can tolerate a wide range of ecological conditions and colonize diverse habitats. Marbled crayfish first appeared in Madagascar in 2005 and quickly spread across the country, overlapping with the distribution of freshwater snails that serve as the intermediate host of schistosomiasis–a parasitic disease of poverty with human prevalence ranging up to 94% in Madagascar. It has been hypothesized that the marbled crayfish may serve as a predator of schistosome-competent snails in areas where native predators cannot and yet no systematic study to date has been conducted to estimate its predation rate on snails. Here, we experimentally assessed marbled crayfish consumption of uninfected and infected schistosome-competent snails (Biomphalaria glabrata and Bulinus truncatus) across a range of temperatures, reflective of the habitat range of the marbled crayfish in Madagascar. We found that the relationship between crayfish consumption and temperature is unimodal with a peak at ~27.5°C. Per-capita consumption increased with body size and was not affected either by snail species or their infectious status. We detected a possible satiation effect, i.e., a small but significant reduction in per-capita consumption rate over the 72-hour duration of the predation experiment. Our results suggest that ecological parameters, such as temperature and crayfish weight, influence rates of consumption and, in turn, the potential impact of the marbled crayfish invasion on snail host populations.
 

Keywords: None provided.

Kaur and colleagues 2023

Kaur D, Iqbal A, Soto I, Kubec J, Buřič M. 2023. Effects of chemical cues and prior experience on predator avoidance in crayfish. Ecology and Evolution 13(8):e10426. https://doi.org/10.1002/ece3.10426

Abstract

Multisensory stimuli provide organisms with information to assess the threat present in the surroundings. Olfactory cues show dominance over other sensory modalities in the aquatic environment. The impact of chemical predator cues combined with experiences gained (learning) in species without previous contact is not fully understood. We investigated the foraging and shelter-seeking behaviour of naïve and experienced marbled crayfish Procambarus virginalis juveniles in response to the chemical signals of pumpkinseed Lepomis gibbosus alone and in combination with alarm chemicals produced by preyed-upon conspecifics. Naïve and experienced (previously exposed to pumpkinseed predation) juveniles were stocked in an arena with shelter and feed and exposed (1) to water from a tank containing a predator actively feeding on conspecifics, (2) water from a tank with predator only and (3) water only as control. Crayfish exposed to the combined stimuli avoided the inlet zone and gravitated to shelter zone of the arena to a greater extent than did those exposed to predator-only cues and the control. Regardless of the treatment, experienced crayfish showed significantly reduced interest in feeding. Our findings imply that crayfish response to threat-associated odours with the greatest potency when visual or tactile cues are present, while previous encounters with predators may make them more cautious.  

Keywords: alarm cues • crayfish • fish • infochemicals • kairomones • predation

Be on the lookout for Marmorkrebs, Ontario! Marmorkrebs finally found in North America

Burlington Today is reporting that Marmorkrebs have been found in Burlington, Ontario.

The details are hazy.

 

Marbled crayfish – an aquatic invasive species that is prohibited in the province – has been found in the Burlington area.

 

That’s the extent of actual reporting. The rest of the article is background information.

Edit, 6 August 2023: A Burlington Post article is a little more expansive.  It gives a general location (a city park).

Previously, another marbled crayfish was reported in the area on iNaturalist. (I actually went to where the iNaturalist sighting was to look around, but heard people had already looked and found nothing.) 

 

This Burlington marbled crayfish sighting is also on iNaturalist, from Premek Hamr, also known as “Dr. Crayfish.” Premek has extensive experience with Ontario crayfish, so it’s not as though this is an Ontario native being misidentified.

 

On Twitter, Hamr has been sharing pictures of multiple individuals, including juveniles. This indicates there is a breeding population at this location.

 

Ontario just banned marbled crayfish last year.

While this is a watershed moment in the worldwide invasive status of marbled crayfish, it is something that has been expected for a long time. It’s mostly surprising in that it didn’t happen a few years ago.

The map of Marmorkrebs introductions has been updated.

External links

Marbled crayfish sighting in iNaturalist

 

Premek Hamr on Twitter: One,  two , three, four

 

Be on the lookout for marbled crayfish in the Burlington area (Burlington Today)

 

‘Capable of cloning’: Invasive crayfish found in Burlington pond (Burlington Post)

‘Capable of cloning’: Invasive crayfish found in Burlington pond (Hamilton Spectator) 

Ontario Natural Resources and Forestry on Twitter

Related posts

Ontario prohibits Marmorkrebs

Musil and colleagues 2023

Musil M, Let M, Roje S, Drozd B, Kouba A. 2023. Feeding in predator naïve crayfish is influenced by cues from a fish predator. Scientific Reports 13: 12265. https://doi.org/10.1038/s41598-023-39406-w

Abstract

In this study, we experimentally evaluated how the feeding behaviour of marbled crayfish Procambarus virginalis is influenced by cues from conspecifics and the round goby Neogobius melanostomus, a fish predator, in tanks that permitted chemical communication but not visual recognition. We used four experimental groups with different combinations in two sub-tanks. The first sub-tank always contained a crayfish and prey (40 individuals of the water louse Asellus aquaticus). The other sub-tanks were set up as follows: (i) empty, serving as a control (C); (ii) with a conspecific crayfish (Cr); (iii) with a round goby (G) to simulate predator-only odour; and (iv) a round goby and three small conspecific crayfish (G + Cr) to simulate the presence of a predator and/or the alarm odour. Two sub-treatments were defined for the fourth group, categorised as ‘injured’ or ‘not injured’ depending on whether prey crayfish were visibly injured or not, respectively. We observed a significant decline in the consumption of water lice in the G and G + Cr treatments compared to the C and Cr treatments (up to 47% on average). There were no significant differences in consumption between the G and G + Cr treatments, or C and Cr treatments. No significant differences in food consumption parameters were detected between sub-treatments with ‘injured’ and ‘not injured’ conspecific crayfish. Knowledge of modifications in the feeding behaviour of marbled crayfish in the presence of round goby (and fish predators in general) is essential for ecologists attempting to understand the changes and impacts occurring in invaded freshwater ecosystems.

 

Keywords: None provided.

Arianoutsou and colleagues 2023

Arianoutsou M, Adamopoulou C, Andriopoulos P, Bazos I, Christopoulou A, Galanidis A, Kalogianni E, Karachle PK, Kokkoris Y, Martinou AF, Zenetos A, Zikos A. 2023. HELLAS-ALIENS. The invasive alien species of Greece: time trends, origin and pathways. NeoBiota 86: 45-79. https://doi.org/10.3897/neobiota.86.101778

Abstract

The current paper presents the first effort to organize a comprehensive review of the Invasive Alien Species (IAS) of Greece. For this purpose, a database was developed with fields of information on the taxonomy, origin, ecology and pathways of introduction of terrestrial, freshwater and marine species. Our database includes a) taxa in the Union’s list that are present in Greece, b) taxa already present in Greece and considered to be invasive, and c) taxa highly likely to enter Greece in the next 10 years and become invasive. The Database served as the starting point for the compilation of the National List of Alien Invasive Species (HELLAS-ALIENS) in compliance with the EU Regulation 1143/2014. Overall, the HELLAS-ALIENS comprises 126 species, i.e. 32 terrestrial and freshwater plant species, 14 terrestrial invertebrates, 28 terrestrial vertebrates, 30 freshwater fishes and invertebrates and 22 marine species. Terrestrial invertebrates, birds and mammals are mainly of Asiatic origin. Most of the terrestrial plants have their native geographical distribution in the Americas (North and South). Most of the freshwater invertebrates and fishes are of North American origin, while the majority of the marine species are of Indo-Pacific origin. The first records of IAS concern terrestrial plant species, and date back to the 19th century, while those in freshwater and marine ecosystems seem to have been systematically recorded some decades later. Regarding the pathways of introduction, most of the taxa arrived in Greece or are expected to arrive through escape from confinement and unaided. The majority of the terrestrial, freshwater and marine species have been evaluated as of High-risk for the indigenous biodiversity and only 3% of the species listed have been evaluated of Low-risk. Our results provide an important baseline for management and action plans, as required by the priorities set by the European Union through the Biodiversity Strategy for 2030.

 

Keywords: European Union • Invasive Alien Species Regulation • pathways of introduction • risk assessments • temporal trends

 

(Note: Marmorkrebs are listed as “Taxa not currently present in Greece but highly likely to be introduced within the next 10 years.”)

Roy 2023

Roy RS. 2023. Identification of gap junction genes involved in the tail-flip escape circuit of marbled crayfish. MSc thesis, Illinois State University. Illinois State University ProQuest Dissertations Publishing. 30313359. https://www.proquest.com/openview/0976de027582da67e16ba85b62d594dc/1

Abstract

Escape responses are highly stereotyped behaviors that enable organisms to avoid threats in their environment. To ensure the rapid and robust execution of these behaviors, they are often mediated by dedicated neuronal circuits with fast feed-forward signal propagation. Rectifying electrical synapses, which allow electrical current to preferentially flow only in one direction, are a hallmark of such circuits, and facilitate rapid and stereotyped neuronal signaling for fast, reflexive behaviors. In vitro studies have suggested that it is the heterotypic distribution of the gap junction proteins (called innexins in invertebrates), i.e., possessing different innexins in pre- and postsynaptic neurons, that enables the rectification of the electrical synapse. However, the presence of distinct pre- and postsynaptic gap junction proteins and the functional roles of these proteins have not been established in escape circuits. I am using the tail-flip escape behavior of crayfish, a classical behavioral model for understanding escape responses, to study gap junction proteins. The neuronal circuitry of the crayfish tail-flip behavior has been largely worked out, with specialized giant neurons identified for the two major types of escape modes in the animal – the lateral giant (LG) and medial giant (MG) tail-flip. In both MG and LG escape circuits, rectifying electrical synapses facilitate rapid signal transmission from primary afferents to the
motor neurons. However, the innexin proteins expressed in the crayfish nervous system and contributing to these rectifying synapses are unknown. To address this gap in knowledge, I use the marbled crayfish (Procambarus virginalis), the only crayfish species with identified genome and transcriptome. Employing bioinformatics, I identified five putative innexin genes (named Inx1 - Inx5), four of which were expressed in the nervous system and likely contribute to tail flip escape responses. Four of the five putative innexins (Inx2 – 5) were expressed in the ventral nerve cord and three of them (Inx2, 3 and 5) were also expressed in the brain. To test the contribution of these innexins to the escape behavior, I used RNA interference to reduce innexin expression. This was followed by behavioral assays to test whether MG and LG tail flips were altered by the RNAi treatment. My results indicate that reduction in expression of two of the five identified innexins, i.e., Inx2 and Inx3, using RNAi resulted in a significant delay in the onset of the LG tail-flip. This suggests that these two innexin proteins contribute to the formation of gap junction channels in the LG tail-flip circuit. In contrast, no significant effect was found for the MG tail-flip following the same RNAi approach. From these results, I conclude that there are four innexin proteins that are expressed in marbled crayfish nervous system and are homologousto other invertebrate innexins. Moreover, marbled crayfish innexin 2 and 3 constitute the gap junction channels that form electrical synapses in the LG tail-flip circuit and are important for robust signal transmission.

Keywords: electrical synapses • giant neurons • gap junctions • innexins • escape response •
tail-flip • RNA interference

Vogt 2023b

Vogt G. 2023. Epigenetics in Crustaceans. In: Piferrer F, Wang H-P (eds.), Epigenetics in Aquaculture, pp. 355-381. https://doi.org/10.1002/9781119821946.ch16

Abstract

This chapter summarizes research on epigenetics in crustaceans and outlines possible applications in crustacean aquaculture. Information on epigenetic mechanisms and their role in gene and phenotype expression, development, ecology, and evolution is mainly available for brine shrimps and water fleas that are cultured as live feed for fish and shellfish larviculture, and for representatives of shrimps, crayfish, and crabs that are cultured for human consumption. The best-investigated crustaceans, with respect to epigenetics, are parthenogenetic lineages of Artemia brine shrimps and Daphnia water fleas and the obligatory parthenogenetic crayfish Procambarus virginalis. Most of the work has been done on DNA methylation followed by histone modifications. The topics studied cover the involvement of epigenetic mechanisms in gene regulation, tissue differentiation, phenotypic variation, development, growth, reproduction, aging, environmental adaptation, resistance to toxicants and pathogens, training of immunity, sex determination, transgenerational inheritance of acquired characters, and speciation. The knowledge gathered has not yet been applied in crustacean aquaculture, but the data suggest that epigenetic interventions have good potential to improve the growth and reproduction of cultured species, manipulate sex, and increase resistance to environmental stressors and diseases.

Artem and colleagues, 2023

Artem O, Oleh M, Iryna H. 2023.  Physiological and biochemical adaptations’ assessment of the marbled crayfish Procambarus virginalis (Lyko, 2017) as an invasive specie (sic) of Ukraine. World Scientific News 182: 57-76. http://www.worldscientificnews.com/article-in-press/2023-2/182-2023/, http://www.worldscientificnews.com/wp-content/uploads/2023/06/WSN-182-2023-57-76.pdf (direct link to PDF)

Abstract

Marbled crayfish are the typical invasive hydrobionts spreaded over the lot of world`s waterbodies and create the populations that can reproduce in the presence of only one triploid female, thereby the threat of biodiversity appears and increase the competition with local species. Due to the appearance of the marbled crayfish Procambarus virginalis (Lyko, 2017) in the open Ukrainian waterbodies, there is necessity to research it`s adaptation possibilities to the ecological factors to predict it`s possible spread and naturalization. The research aim was to determine the physiological and biochemical features of the adaptations of marbled crayfish as a new species inhabiting the aquatic ecosystems of Ukraine under the conditions of toxicological load on the aquatic ecosystem. The obtained research results indicate significant changes in individual cytological and biochemical indicators of marbled crayfish under the impact of heavy metal ions. A change in these parameters may indicate a rapid cellular response of the crustacean species to the toxic effect of heavy metals. These indicators can be used in the future in studying the adaptation of marbled crayfish in natural waterbodies.

Keywords: heavy metals • marble crayfish • physiology • adaptation

Roy and collegues 2023

Roy K, Das K, Petraskova E, Kouba A. 2023. Protein from whole-body crayfish homogenate may be a high supplier of leucine or branched-chain amino acids – A call for validation on genus Procambarus sp. Food Chemistry 427: 136728. https://doi.org/10.1016/j.foodchem.2023.136728

Abstract

Essential proteinogenic branched-chain amino acids (BCAA), particularly leucine (Leu) have been investigated for their role in enhancing human myofibrillar protein synthesis and biomedical research on tumor models. However, only a few protein sources in our current foor system have high enough BCAA or Leu coefficients (% of total amino acids) to be considered as supplements for food, sport, or biomedical research. Mostly dairy-sourced proteins such as casein and whey or rarely plant source such as maize gluten are typically regarded as the gold standards. This study hypothesized that protein isolates derived from the whole-body homogenate (including the chitinous exoskeleton) of procambarid crayfish might exhibit unusually high BCAA and Leu content. The study provides open-access data on the amino acid compositions of two procambarid crayfish (Procambarus virginalis and P. clarkii), as well as a comparison with casein. The mentioned crayfish species could offer 6.36–7.39 g Leu 100 g⁻¹ dry matter (at 43–48% protein only). Crayfish whole-body protein isolates exhibit a Leu coefficient (18.41±2.51% of total amino acids) and a BCAA coefficient (28.76±2.39% of total amino acids), which is comparable to or higher than of casein (Leu coefficient 8.65±0.08%; BCAA coefficient 20.03±0.73%). However, it is important to interpret these results with caution, due to the challenges associated with leucine and isoleucine separation, as well as potential interactions within the sample matrices. Hence, international validation of these findings is recommended.

 

Keywords: crayfish protein • human muscle protein synthesis • leucine isoleucine valine • amino acids

Kor and colleagues, 2023b

Kor G, Mengal K, Buřič M, Kozák P, Niksirat H. 2023. Granules of immune cells are the source of organelles in the regenerated nerves of crayfish antennae. Fish & Shellfish Immunology 137: 108787. https://doi.org/10.1016/j.fsi.2023.108787

 

Abstract

Regeneration refers to the regrowing and replacing of injured or lost body parts. Crayfish antennae are nervous organs that are crucial for perceiving environmental signals. Immune cells (hemocytes) are responsible for neurogenesis in crayfish. Here, we used transmission electron microscopy to investigate at ultrastructural levels the potential roles of immune cells in nerve regeneration in crayfish antennae after amputation. The results showed that, while all three types of hemocytes were observed during nerve regeneration, granules of semi-granulocytes and granulocytes are the main sources of new organelles such as mitochondria, the Golgi apparatus and nerve fibres in the regenerated nerves of crayfish antennae. We describe the transformation of immune cell granules into different organelles in the regenerating nerve at ultrastructural levels. Also, we observed that the regeneration process speeds up after crayfish moulting. In conclusion, the granules are compacted packages of versatile materials carried by immune cells and can be converted into different organelles during nerve regeneration in crayfish antennae.

Keywords: None.

Mengal and colleagues, 2023b

Mengal K, Kor G, Siino V, Buřič M, Kozák P, Levander F, Niksirat H. 2023. Quantification of proteomic profile changes in the hemolymph of crayfish during in vitro coagulation. Developmental & Comparative Immunology 147: 104760. https://doi.org/10.1016/j.dci.2023.104760

Abstract

Hemolymph is the circulatory fluid that fills the body cavity of crustaceans, analogous to blood in vertebrates. Hemolymph coagulation, similar to blood clotting in vertebrates, plays a crucial role in wound healing and innate immune responses. Despite extensive studies on the clotting process in crustaceans, no comparative quantitative analysis of the protein composition of non-clotted and clotted hemolymph in any decapod has been reported. In this study, we used label-free protein quantification with high-resolution mass spectrometry to identify the proteomic profile of hemolymph in crayfish and quantify significant changes in protein abundances between non-clotted and clotted hemolymph. Our analysis identified a total of two-hundred and nineteen proteins in both hemolymph groups. Furthermore, we discussed the potential functions of the top most high and low-abundant proteins in hemolymph proteomic profile. The quantity of most of the proteins was not significantly changed during coagulation between non-clotted and clotted hemolymph, which may indicate that clotting proteins are likely pre-synthesized, allowing for a swift coagulation response to injury. Four proteins still showed abundance differences (p < 0.05, fold change>2), including C-type lectin domain-containing proteins, Laminin A chain, Tropomyosin, and Reverse transcriptase domain-containing proteins. While the first three proteins were down-regulated, the last one was up-regulated. The down-regulation of structural and cytoskeletal proteins may affect the process of hemocyte degranulation needed for coagulation, while the up-regulation of an immune-related protein might be attributed to the phagocytosis ability of viable hemocytes during coagulation.

 

Keywords: None.

Xiao and Faulkes 2023

Xiao J, Faulkes Z. 2023. Online advertisements for crayfish decrease after a provincial ban. ARPHA Preprints. https://preprints.arphahub.com/article/107487, https://doi.org/10.3897/arphapreprints.e107487 (DOI link not working yet)

Abstract

The parthenogenetic marbled crayfish, Procambarus virginalis, is an unwanted species introduced in many countries. There are no established populations in North America to date. Several jurisdictions in the United States and Canada have specifically banned ownership of marbled crayfish, but it is unclear if such bans effectively reduce ownership. The Canadian province of Saskatchewan prohibited marbled crayfish in 2020. We tested whether the introduction of this law affected behaviour by comparing online advertisements for crayfish in Saskatchewan and other Canadian provinces over two years before and after the ban. The number of online advertisements and sellers in Saskatchewan for all crayfish – not just marbled crayfish – was significantly smaller after the ban. No other province showed this pattern. This suggests banning marbled crayfish reduced the online availability of crayfish and may be an example of a successful policy to reduce availability of aquarium pets.

Keywords: Marmorkrebs • crayfish • pet trade • aquarium • policy

Note: This is an unreviewed preprint.

 

CrayIT 2023 meeting

CrayfIT is a regional Europoean crayfish meeting that will be held this September.

The meeting will be held at the University of Pavia.

Besides the usual talks and posters, there will be a field trip to the North-Western Apennines to see visit lowland sites for Procambarus clarkii and hilly sites for Austropotamobius pallipes.

Early bird registration deadline is 2 May.

External links

CrayfIT meeting site
 

Aigner 2022

Aigner K. 2022. Ecology of marbled crayfish and possible management measures at fishing ponds in Salzburg. Master’s thesis, Department of Environment and Biodiversity, University of Salzburg. https://resolver.obvsg.at/urn:nbn:at:at-ubs:1-36654

Abstract

Exotic crayfish species are threatening native freshwater ecosystems as well as native crayfish species by affecting all trophic levels of a system, competition and being a vector of the crayfish plague pathogen. The highly invasive marbled crayfish (Procambarus virginalis) is very successful in establishing populations in the wild, due to its parthenogenetic form of reproduction. Three established populations were found at fishing ponds in Salzburg and investigated over a period of ten weeks to shed light on habitat requirements or preferences of this species as well as evaluating and comparing methods for detection and catch. Water temperature and dissolved oxygen concentration, as well as time of the year and macrophyte cover were the main factors affecting the density of active marbled crayfish in this study. Additionally, the obtained data from observations suggests a preference of marbled crayfish for structure-rich habitats providing shelters as well as food sources. Traditional crayfish traps were the most size-selective catching method, followed by fine-meshed fish traps. Hand-catch with landing nets showed no size-selectivity. In almost all samples the eDNA analyses indicated no presence of marbled crayfish, despite numerous observations at night. The false negative results of this method were likely due to insufficient filtering volumes and a low number of sub-samples. qPCR analyses of twenty individuals showed no sign of infection with the crayfish plague pathogen (Aphanomyces astaci), hinting that the population might not have encountered this pathogen yet. The results of this study provide a first insight into the ideal habitats for marbled crayfish. However, this species is known for its high ecological plasticity, which is why further investigations are strongly recommended. Additionally, management measures to supress (sic) population growth in order to avoid a spread to other freshwater systems in close proximity should be continuously undertaken as well as monitoring regarding the infection status with the crayfish plague pathogen.

 

Keywords: Marbled crayfish • Procambarus virginalis • Austria • habitat preferences • population characteristics • management measures • eDNA • crayfish plague • invasive species

Kor and colleagues 2023

Kor G, Mengal K, Buřič M, Kozák P, Niksirat H. 2023. Comparative ultrastructure of the antennae and sensory hairs in six species of crayfish. PeerJ 11: e15006. https://doi.org/10.7717/peerj.15006 

 

Abstract

 

Background

Antennae in crayfish are essential for gaining information about the local topography and localising food, chemicals, conspecifics or predator. There are still gaps in the research on the morphology of antennae in decapods compared to other arthropods.

 

Methodology 

Biometrical and ultrastructural methods were applied using light and cryo-scanning electron microscopies to study the morphology of antennae in six different crayfish species, including marbled crayfish Procambarus virginalis, Mexican dwarf crayfish Cambarellus patzcuarensis, red swamp crayfish Procambarus clarkii, signal crayfish Pacifastacus leniusculus, common yabby Cherax destructor, and spiny-cheek crayfish Faxonius limosus to find their potential morphological differences.

 

Results

Significant differences in the antenna length, length and width of each segment to carapace length ratios, and the number of segments were found in the six crayfish species. The ultrastructure revealed differences in the distribution of sensory hairs on the antenna and the morphology of the antennal surface.

 

Conclusions

The different morphology of antennae might reflect adaptation to the conditions of their specific habitats. In addition, results showed that a combination of differences in the morphological features and biometrical measurements of antennae could be used for the distinguishment of different studied crayfish species.

 

Keywords: antenna • arthropods • biometry • electron microscopy • morphology • crustaceans

Mengal and colleagues, 2023

Mengal K, Kor G, Kouba A, Kozák P, Niksirat H. 2023. Hemocyte coagulation and phagocytic behavior in early stages of injury in crayfish (Arthropoda: Decapoda) affect their morphology. Developmental & Comparative Immunology 141: 104618. https://doi.org/10.1016/j.dci.2022.104618

Abstract

Crustacean hemocytes are important mediators of immune functions such as coagulation and phagocytosis. We employed an in situ approach to investigate the ultrastructural behavior of hemocytes during coagulation and phagocytosis in the early stages after injury caused by leg amputation, using transmission electron microscopy technique in marbled crayfish Procambarus virginalis. Hemocytes underwent drastic morphological changes during coagulation. The morphology of the cytoplasmic granules changed from electron-dense to electron-lucent forms in an expanding manner. The transformed granules containing amorphous electron-lucent material were observed to merge and discharge their contents into extracellular space for coagulation. We also observed that the contents of the nucleus participate in the process of coagulation. In addition, leg amputation induced extensive muscle degeneration and necrotic tissues were avidly taken up by the phagocytic hemocytes containing distinct phagosomes. Interestingly, we observed for the first time how the digested contents of phagocytized necrotic tissues are incorporated into granules and other cellular components that change the cell morphology by increasing the granularity of the hemocytes. Nevertheless, the degranulation of hemocytes during coagulation can also reduce their granularity. Given that morphological traits are important criteria for hemocyte classification, these morphological changes that occur during coagulation and phagocytosis must be taken into account.

Keywords: degranulation • hemolymph coagulation • muscle degeneration • phagocytosis

Marbled crayfish on TikTok

I’m not a big TikTok user, but a research search came up with a decently long list of Marmorkrebs videos on TikTok.

Vogt 2023

Vogt G. 2023. Environmental adaptation of genetically uniform organisms with the help of epigenetic mechanisms—An insightful perspective on ecoepigenetics. Epigenomes 7(1): 1. https://doi.org/10.3390/epigenomes7010001

Abstract

Organisms adapt to different environments by selection of the most suitable phenotypes from the standing genetic variation or by phenotypic plasticity, the ability of single genotypes to produce different phenotypes in different environments. Because of near genetic identity, asexually reproducing populations are particularly suitable for the investigation of the potential and molecular underpinning of the latter alternative in depth. Recent analyses on the whole-genome scale of differently adapted clonal animals and plants demonstrated that epigenetic mechanisms such as DNA methylation, histone modifications and non-coding RNAs are among the molecular pathways supporting phenotypic plasticity and that epigenetic variation is used to stably adapt to different environments. Case studies revealed habitat-specific epigenetic fingerprints that were maintained over subsequent years pointing at the existence of epigenetic ecotypes. Environmentally induced epimutations and corresponding gene expression changes provide an ideal means for fast and directional adaptation to changing or new conditions, because they can synchronously alter phenotypes in many population members. Because microorganisms inclusive of human pathogens also exploit epigenetically mediated phenotypic variation for environmental adaptation, this phenomenon is considered a universal biological principle. The production of different phenotypes from the same DNA sequence in response to environmental cues by epigenetic mechanisms also provides a mechanistic explanation for the “general-purpose genotype hypothesis” and the “genetic paradox of invasions”.

Keywords: asexual populations • epigenetic ecotypes • ecoepigenetics • DNA methylation • environmental adaptation • general-purpose genotype • invasion paradox • phenotypic plasticity