18 July 2024

Kaur and colleagues 2023

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Kaur D, Iqbal A, Soto I, Kubec J, Buřič M. 2023. Effects of chemical cues and prior experience on predator avoidance in crayfish. Presentation given to CrayfIT 2023 conference. https://crayfit.eu/wp-content/uploads/2023/09/Crayfit-Book-of-Abstracts.pdf


Multisensory stimuli provide organisms with information to assess the threat present in the surroundings. The impact of the chemical predatory cues combined with experiences gained between species previously unknown to each other was not fully understood. We investigated the foraging and behaviour of naïve and experienced marbled crayfish (Procambarus virginalis) juveniles in response to the chemical signals of pumpkinseed (Lepomis gibbosus) alone, and during the active foraging on the marbled crayfish juveniles. Naïve and experienced crayfish juveniles were exposed to three different conditions: the water inlet came from 1) a tank with predator actively foraging on their conspecifics, 2) the a from tank with predator only, and 3) from an empty tank. Crayfish behaviour in arenas with food and shelter was video recorded for 4 hours. The positions of crayfish in specific zones in the arena (inlet, transition, and shelter zone) were localized every five minutes. Feed consumed was measured after the trial. The results obtained indicated that crayfish exposed to the combined stimuli avoided the inlet zone and preferred the shelter zone of the arena to a greater extent than did those crayfish exposed to predator-only cues and the control. Regardless of the stimuli, experienced crayfish showed significantly reduced foraging. Crayfish juveniles were more cautious because of previous experience rather than due to scent perception. Our findings imply that crayfish respond to threat-associated
odours with the greatest potency when visual or tactile cues are present, but previous experience with predator can cause high precaution.

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

17 July 2024

Stein and colleagues 2022

Stein W, DeMaegd ML, Benson AM, Roy RS, Vidal-Gadea AG. 2022. Combining old and new tricks: The study of genes, neurons, and behavior in crayfish. Frontiers in Physiology 13: 947598. https://doi.org/10.3389/fphys.2022.947598


For over a century the nervous system of decapod crustaceans has been a workhorse for the neurobiology community. Many fundamental discoveries including the identification of electrical and inhibitory synapses, lateral and pre-synaptic inhibition, and the Na+/K+-pump were made using lobsters, crabs, or crayfish. Key among many advantages of crustaceans for neurobiological research is the unique access to large, accessible, and identifiable neurons, and the many distinct and complex behaviors that can be observed in lab settings. Despite these advantages, recent decades have seen work on crustaceans hindered by the lack of molecular and genetic tools required for unveiling the cellular processes contributing to neurophysiology and behavior. In this perspective paper, we argue that the recently sequenced marbled crayfish, Procambarus virginalis, is suited to become a genetic model system for crustacean neuroscience. P. virginalis are parthenogenetic and produce genetically identical offspring, suggesting that germline transformation creates transgenic animal strains that are easy to maintain across generations. Like other decapod crustaceans, marbled crayfish possess large neurons in well-studied circuits such as the giant tail flip neurons and central pattern generating neurons in the stomatogastric ganglion. We provide initial data demonstrating that marbled crayfish neurons are accessible through standard physiological and molecular techniques, including single-cell electrophysiology, gene expression measurements, and RNA-interference. We discuss progress in CRISPR-mediated manipulations of the germline to knock-out target genes using the ‘Receptor-mediated ovary transduction of cargo’ (ReMOT) method. Finally, we consider the impact these approaches will have for neurophysiology research in decapod crustaceans and more broadly across invertebrates.


Keywords: marbled crayfish • CRISPR • tail flip • stomatogastric ganglion • marmorkrebs • giant fiber • RNAi • transgenesis

Steen and colleagues 2023

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Steen F, Scheers K, De Knijf G. 2023. Controlling Marbled Crayfish in an urban pond: a dual approach involving intensive trapping and predator introduction. Presentation given to CrayfIT 2023 conference. https://crayfit.eu/wp-content/uploads/2023/09/Crayfit-Book-of-Abstracts.pdf


The marbled crayfish is a newly introduced invasive species in the Flanders region of Belgium, first sighted in 2017. The species has primarily been sighted in artificial ponds in urbanised areas, suggesting its introduction through the release of aquarium pets. Marbled Crayfish have not yet spread to open water systems in Belgium, presenting an opportunity to experiment with control measures within a closed system. To manage this species within the urban park pond in the municipality of Westende, a pilot study was developed. The municipality did not approve of draining the pond, and the use of chemical agents is prohibited in aquatic environments in Flanders. To comply with these restrictions, we developed an alternative management measure to decrease crayfish densities and minimise the risk of spread. A dual approach will be implemented, involving an intensive catch event followed by the introduction of two fish species, Cyprinus carpio and Lota lota to further suppress the population. Electrofishing and baited crayfish traps will be used to achieve a proportional reduction in densities at the start of the reproductive season. The introduction of fish is aims at preventing juvenile crayfish from reaching the reproductive phase, by creating a year-round predation pressure with common carp predating from spring to autumn, and burbot throughout the winter. This dual approach will be tested to
determine its effectiveness in controlling marbled crayfish densities. Preliminary results obtained after the first two phases of the study, namely population reduction and the introduction of the common carp, will be presented.

Keywords: Marbled Crayfish, invasive species management

Ložek and Vojs Staňová 2023

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Ložek F, Vojs Staňová A. 2023. A rare observation of conjoined twins in marbled crayfish Procambarus virginalis. Presentation given to CrayfIT 2023 conference. https://crayfit.eu/wp-content/uploads/2023/09/Crayfit-Book-of-Abstracts.pdf


Conjoined twins in crustaceans, including crayfish, have been predominantly observed during early developmental stages. However, cases of conjoined twins surviving into juvenile stages are infrequent and often associated with mortality resulting from complications during moulting due to morphological abnormalities. In this study, we present a unique case of marbled crayfish conjoined twins that remained viable for 36 days post-hatch, progressing into the 3rd juvenile stage with the ability to moult. The fused individuals exhibited separate complete anteroposterior body axes, conjoined along the dorsal side of the cephalothorax. Both twins demonstrated successful predation of living nauplii of Artemia salina, their provided food source. Nonetheless, reduced mobility led to the growth of epibionts on their body surface, ultimately hindering the moulting process. This exceptional case sheds light on the prolonged survival and functional capabilities of conjoined twins in crayfish, expanding our understanding of their developmental biology.

Keywords: decapods, developmental aberration, parthenogenesis, genetic anomalies

14 July 2024

Teesalu and colleagues 2023

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Teesalu P, Maria-Muuga J, Hurt M, Kaldre K, Nõges T, Ercoli F. 2023. The role of temperature in marbled crayfish (Procambarus virginalis, Lyko 2017) invasion in Estonian freshwater ecosystem. Presentation given to CrayfIT 2023 conference. https://crayfit.eu/wp-content/uploads/2023/09/Crayfit-Book-of-Abstracts.pdf. Slide deck: https://dspace.emu.ee/server/api/core/bitstreams/9c9a5f04-fffc-4e21-b450-7c8b22650b94/content


Marbled crayfish (Procambarus virginalis) is an example of a freshwater invader spreading
across Europe, and understanding its establishment and distribution is crucial. This study
aimed to assess the role of temperature in the invasion of marbled crayfish in the artificially
warm outflow channel of a power plant in Estonia. It was hypothesized that warmer water
temperature and the temperature gradient along the channel would impact crayfish
establishment, distribution, and trophic niche. Temperature loggers recorded a gradient,
revealing that the channel was significantly warmer than the reservoir, providing a suitable
habitat for crayfish. Stable isotope analyses showed spatial and seasonal trophic niche
shifts. The crayfish diet at the channel head mainly consisted of macroinvertebrates and
macrophytes, while the mouth had a diet dominated by periphyton. Additionally, the
crayfish shifted from consuming primary consumers in spring to primary producers in
autumn. Temperature played a crucial role in crayfish establishment, but other factors like
food source availability likely influenced population distribution. Overall, this research
sheds light on the importance of temperature and ecological aspects in the invasion
dynamics of marbled crayfish.


Keywords: stable isotopes • trophic niche • invasive species • population dynamic •
temperature effect

13 July 2024

Kaliberda and colleagues 2024

Kaliberda A, Marenkov O, Kaliberda N. 2024. The use of albuvir to produce a life-sustaining young crayfish. In: Modern Scientific and Technical Research in the Context of Linguistic Space (in English): Conference materials of the III All-Ukrainian scientific and practical conference of young scholars and students. 355 pp. Dnipro: Bila K. O. https://www.dnu.dp.ua/docs/ndc/2024/materiali_konferenc/13.pdf#page=18


(First paragraph only.) 


Marbled crayfish or Marmorkrebs (Procambarus virginalis) is a perspective species in aquaculture and water areas because a single individual is only needed to establish a new population, and they can reproduce athletes. Therefore, it is important to clarify the biological aspects of its breeding and the influence of biological additives «Albuvir» on the young generation`s vitality. Albuvir is a broad-spectrum antiviral agent. The drug is a composition of acidic peptides capable of self-organization and
self-adaptation in the body. Their mechanism is based on the blockade of nuclear import peptides and prevents import from the viral genome from crossing the nuclear membrane. An interesting detail is that adaptation to the drug is impossible for the virus and for the animal organism because the drug is a quasi-living self-organizing system and its composite pharmacophore is unique for each animal and virus. Marbled crayfish is reproduced by means of parthenogenesis – an asexual reproduction in which a female can produce an embryo without fertilizing an egg with sperm. As a result, their offspring is genetically identical, which makes this species is the best research object.


Keywords: None provided.

Heinz and Wenninger, 2024

Cover of "Journal of Zoo and Wildlife Medicine" featuring a cat.
Heinz J, Wenninger M. 2024. Evaluation of immersion in emulsified isoflurane or propofol as part of a two-step euthanasia protocol in marbled crayfish (Procambarus virginalis). Journal of Zoo and Wildlife Medicine 55(2): 424-429. https://doi.org/10.1638/2023-0137


The marbled crayfish (Procambarus virginalis) is a parthenogenetic invasive species across much of the world, and when found, euthanasia is often recommended to reduce spread to naïve ecosystems. Euthanasia recommendations in crustaceans includes a two-step method: first to produce nonresponsiveness and then to destroy central nervous tissue. Minimal data exist on adequate anesthetic or immobilization methods for crayfish. A population of 90 marbled crayfish was scheduled for euthanasia due to invasive species concerns. The population was divided into six treatment groups to evaluate whether immersion in emulsified isoflurane or propofol solutions could produce nonresponsiveness. Each group was exposed to one of six treatments for 1 h: isoflurane emulsified at 0.1%, 0.5%, 2%, 5%, and 15% or propofol at 10 mg/L and then increased to 100 mg/L. Crayfish from all treatment groups were moved to nonmedicated water after completion of 1 h and observed for an additional 4 h. All crayfish treated with isoflurane showed lack of a righting reflex at 5 min and loss of movement after 30 min. By 240 min (4 h), none of the crayfish from the isoflurane treatment groups regained movement. None of the crayfish in the propofol treatment achieved loss of reflexes or responsiveness, and all remained normal upon return to nonmedicated water. Isoflurane emulsified in water produces nonresponsiveness that is appropriate for the first step of euthanasia, while propofol was insufficient at these treatment doses.

Keywords: None provided.