Shkurov and colleagues 2026

Shkurov AY, Ostras DA, Harkavenko VV. 2026. Effects of caffeine exposure on the behavior of the invasive marbled crayfish Procambarus virginalis. In: Pilay AP (Editor-in-chief), VetBioConnect: Young Scientists Conference, 3-4 June 2026, Kharkiv, pp. 91-93. https://doi.org/10.36016/VBC-2026 (Abstract only.)

Background. Caffeine is a widespread pharmaceutically active compound that enters surface waters mainly with municipal wastewater and may alter the behavior of aquatic organisms even at sublethal concentrations. Behavioral endpoints are especially important in ecotoxicology because changes in movement, shelter use, social interactions, and aggression can affect survival, dispersal, and population-level responses before mortality occurs. Crayfish are suitable model organisms for such studies because they demonstrate distinct spatial, social, and agonistic behavior that can be recorded and quantified under laboratory conditions. The marbled crayfish Procambarus virginalis is of particular interest because it is a parthenogenetic, highly plastic, and invasive species capable of rapidly establishing new populations from aquarium releases. For invasive hydrobionts, pollutant-induced behavioral changes may influence both individual stress tolerance and the ecological success of populations in transformed freshwater ecosystems. Previous studies have shown that psychoactive pollutants can modify locomotor activity, shelter-related behavior, and risk-taking in aquatic invertebrates, including crayfish. However, the behavioral effects of caffeine on P. virginalis remain insufficiently described. Therefore, short- term laboratory exposure combined with ethogram-based video analysis can provide useful preliminary data on how this invasive crayfish responds to caffeine contamination.

 

Aim. The aim of this study was to evaluate the effects of caffeine exposure on  the behavioral structure of the invasive marbled crayfish Procambarus virginalis and  to describe the temporal dynamics of changes in locomotor, anxiety-related, shelter- related, and aggressive activity over 24 hours.

 

Materials and methods. The study was carried out under laboratory conditions using video recording followed by ethogram analysis in BORIS software. Marbled crayfish were kept in an open 20 L container. In the control series, baseline behavior was recorded without the addition of any substance. In the experimental series, behavior was recorded after a single addition of caffeine at a dose of 200 mg per 20 L of water, corresponding to 10 mg/L. Behavior was assessed at 0, 6, 12, and 24 h after exposure. The duration and frequency of the following behavioral categories were analyzed: Move, Rest, Swim, Shelter, Wall, Field, Aggression, Attacking pose, and Ball of crayfish. The control and experimental observations were compared to identify changes in the distribution of behavioral forms and in the temporal structure of activity.

 

Results. In the control group, the behavioral profile remained relatively stable throughout the observation period: Rest predominated (60‒68% of the time), locomotor activity remained moderate (15‒22%), and aggressive or anxiety-related reactions were rare. During the first 10 min after caffeine addition, crayfish demonstrated pronounced hyperactivity and stress-related orientation: Move increased to 33.5%, Wall to 12.5%, Ball of crayfish to 18.9%, and Attacking pose to 18.7%. After 6 h, the behavioral pattern changed sharply: Rest reached 86.3%, whereas Aggression increased to 25.0% and Attacking pose to 25.7%, indicating motor exhaustion combined with persistent social tension. After 12 h, locomotor activity almost disappeared (Move 0.6%), while Attacking pose remained high (24.8%), suggesting postural tension under conditions of minimal mobility. After 24 h, Rest again predominated (73.9%), Aggression decreased to 6.6%, Attacking pose decreased to 4.2%, and episodic shelter use appeared.

 

Conclusions. Caffeine exposure caused a phase restructuring of the behavioral pattern of P. virginalis: from acute hyperactivity and anxiety through aggressive exhaustion to a relatively stable state of low-mobility adaptation. The results indicate that the behavior of marbled crayfish may be used as a sensitive indicator of caffeine and other pharmaceutical pollutants in aquatic environments. This approach can be applied in further studies of behavioral ecotoxicology of invasive hydrobionts and in the assessment of ecological risks in transformed freshwater ecosystems.

 

Keywords: marbled crayfish • Procambarus virginalis • caffeine • behavioral responses • invasive species • ecotoxicology.

Pipinić and colleagues, 2026

Pipinić K; Marn N; Hudina S. 2026. Effects of Multiple Stressors on the Crayfish– Pathogen Dynamics in Freshwater Ecosystems – A PhD Research Plan. In: Petrović Popović P, Popović M (eds.), Book of Abstracts of 10th Faculty of Science PhD Student Symposium. University of Zagreb Faculty of Science: Zagreb. https://www.croris.hr/crosbi/publikacija/prilog-skup/947642 (Direct link to PDF of conference abstract booklet: https://www.croris.hr/crosbi/publikacija/knjiga/940582)

 

Abstract

Host–pathogen dynamics have been extensively researched in model organisms of crayfish plague (Aphanomyces astaci Schikora, 1906) and freshwater crayfish. Invasive crayfish species introduced into European freshwater ecosystems are relatively tolerant of the disease due to their long coevolutionary history. They are considered vectors of crayfish plague when introduced to novel environments. Simultaneously, native populations are being decimated because they are more susceptible to the disease. A growing body of evidence suggests that similar coevolutionary processes are emerging between European crayfish and A. astaci. Host–pathogen dynamics are a key determinant of population viability, shaped by the complex interplay among the host, the pathogen, and the environment. However, how these interactions shift under global stressors such as climate change and pollution remains largely unexplored. The response to different stressors has been studied individually for crayfish plague, the native species Astacus astacus (Linnaeus, 1758), and the invasive species Procambarus virginalis Lyko, 2017. Our study aims to test the effects of multiple stressors (temperature and microplastic pollution) on the host–pathogen dynamic. We will experimentally test the exposure of A. astacus and P. virginalis to different temperature regimes, pathogen, and microplastics mixture, as well as combinations of the three stressors, and analyse their individual and joint effects on crayfish fitness (survival, growth rate, body condition and reproductive capacity). The results of our experiments will be used to train dynamic energy budget (DEB) models for both crayfish species. At the beginning of our study, we hypothesise that multiple stressors will have a greater impact on the fitness of the native species than on that of the invasive species. With DEB models, we will be able to predict tipping points at which significant metabolic responses and possible loss of native populations are expected. Tipping points may indicate conditions that negatively affect the invasive potential of P. virginalis. This poster will present the experimental design, aim, and expected results of our study. 

 

Keywords: Aphanomyces astaci • Astacus astacus • Procambarus virginalis • modelling

Slusar and colleagues 2026

Slusar M, Muzhenko A, Kovalchuk S, Fedorovych Ye, Ishchuk O, Mamchenko V, Svitelskyi M. 2026. Comparative characteristics of physicochemical parameters of meat and biochemical composition of hemolymph in three species of crayfishes. Studia Biologica 20(2): 31-46. https://doi.org/10.30970/sbi.2002.887

Abstract

Background. Crayfish farming is a promising direction in the development of aquaculture. Compared with marine crustacean species, freshwater crayfish require lower cultivation costs, while their meat is regarded as an additive dietary delicacy with a high nutritional value. The aim of this study was to compare the morphological and physiological data (slaughter yield, taste quality, physicochemical composition of meat, and some biochemical indexes of hemolymph) of three species of adult crayfishes, i.e.Australian red claw crayfish (Cherax quadricarinatus), narrow-clawed crayfish (Astacus leptodactylus), and marbled crayfish (Procambarus fallax forma virginalis), which were cultivated in a recirculating aquaculture system.

 

Materials and Methods. Organoleptic and physicochemical methods were used to assess meat quality, while biochemical methods were applied to determine hemolymph parameters in the abovementioned crayfish species.

 

Results. The results showed that the edible portion relative to live weight was 15.16 ± 0.20 % in the Australian redclaw crayfish, 12.16 ± 0,21 % in the Marbled crayfish, and 9.40 ± 0,19 % in the Narrow-clawed crayfish. The highest protein content in meat was observed in marbled crayfish (17.4 ± 0.84 %). The highest fat content was registered in Australian redclaw crayfish (0.95 ± 0.024 %); for the marble crayfish, this value was 0.9 ± 0.03 %, and for the narrow-clawed crayfish, it was 0.9 ± 0.35 %. No
differences were found in carbohydrate content among the studied species; the value of this parameter was approximately 1.2 ± 0.02 % in all the crayfish species. The meat of Australian redclaw crayfish exhibited the highest energy value (76.1 ± 3.12 kcal/100 g), exceeding that of the other species by 1.3 – 2.2 kcal/100 g, marbled crayfish – 74.8 ± 3.69 kcal/100 g, and narrow-clawed crayfish ‒ 73.9 ± 3.52 kcal/100 g, respectively. In terms of hemolymph protein content, Australian redclaw crayfish showed the highest level (77.1 ± 2.87 g/L), for the narrow-clawed crayfish, this value was (64.9 ± 2.90 g/L), and for the marbled crayfish, it was (57.2 ± 2.41 g/L).

 

The highest calcium concentration in hemolymph was observed in narrow-clawed crayfish (9.52 ± 0.212 mmol/L), while comparable levels were recorded in Australian redclaw (7.99 ± 0.215 mmol/L) and marbled crayfish (7.42 ± 0.292 mmol/L). Differences in all studied indicators were considered statistically significant at p ≤ 0.05.

 

Conclusions. The study results obtained for Australian red claw crayfish, narrow-clawed crayfish and marbled crayfish allow us to evaluate their productivity and meat nutritional validity, as well as to propose the reference ranges of key indexes which can be used in optimizing aquaculture technologies and production of high-quality delicacies or supporting food products.

 

Keywords: crayfish aquaculture • Australian red claw crayfish (Cherax quadricarinatus) • narrow-clawed crayfish (Astacus leptodactylus) • marbled crayfish (Procambarus fallax forma virginalis) • slaughter yield • meat productivity • hemolymph • reference indexes

 

Poirier and colleagues 2026

Poirier LA, Pratt CJ, Hope E, Kingsbury S, McAlpine DF, LeBlanc F, Burbidge C. 2026. First record of the nonindigenous crayfish, Procambarus virginalis Lyko, 2017, in Nova Scotia, Canada. BioInvasions Records 15(2): 393-402. https://doi.org/10.3391/bir.2026.15.2.14

Abstract

Herein, we report the first record of the cambarid marbled crayfish (Procambarus virginalis Lyko, 2017) in the province of Nova Scotia, Canada. Originating from the pet trade in Germany, the marbled crayfish is a parthenogenic species that is known to be a rapid colonizer of multiple habitat types and can outcompete native species. Multiple collections of specimens were made during 2023 and 2024 in two small backyard ponds in the southwestern area of the province. Genetic confirmation was completed by sequencing a portion of the mitochondrial cytochrome c oxidase subunit 1 (CO1) gene using universal marine invertebrates PCR primers. A 100% match was obtained to publicly available DNA reference sequences. This species represents a potential threat to Nova Scotian waterways, as disruptions to food web organization are anticipated. With limited options for eradication and control, the potential for the mitigation or reversal of invasion impacts is low.

Keywords: marbled crayfish • range expansion • crawfish • introduction • vectors 

 

Mengal and colleagues, 2026

Mengal K, Kor G, Siino V, Levander F, Niksirat H. 2026. Effects of acute cold and heat shocks on the protein profile of crayfish hemolymph: Implications for crustacean adaptation to thermal stress. Aquaculture Reports 46: 103265. https://doi.org/10.1016/j.aqrep.2025.103265

 

Abstract

 

Temperature, a key environmental stressor, can induce changes at the molecular levels in the body of living beings, which are necessary for adaptation and survival under altered conditions. We investigated the effects of acute cold (3 °C) and heat (32 °C) shocks on hemolymph protein profiles in marbled crayfish. Results showed that cold shock induced a metabolic shift toward glucose production by increasing enzymes for breaking down glycogen and upregulating enzymes related to glycolysis, such as glycogen phosphorylase, glyceraldehyde-3-phosphate dehydrogenase, enolase, and L-lactate dehydrogenase in the hemolymph of crayfish. The upregulation of proteins such as filamin-A, alpha-actinin, and tubulin beta may indicate that immune cells in the hemolymph strengthen their survival during cold stress through reinforcement of the cytoskeletal rigidity. Shifts in the abundance of immunity-related proteins such as masquerade-like and β-1,3-glucan-binding proteins suggest that the immune system of decapods can adapt to thermal stresses via remodeling the extracellular matrix and pattern recognition receptors, ultimately modulating host defense strategies by shifting between phagocytosis and melanization. Furthermore, the regulation of reproduction-associated proteins indicates that thermal shock may affect the capacity for reproduction. These findings offer insight into how decapods cope with thermal stresses and may support strategies to protect them in farmed environments, especially under climate change. Data are available via ProteomeXchange with identifier PXD065043. 

Keywords: decapod • proteomics • temperature • marbled crayfish • thermal stress

Balzani and colleagues 2025

Balzani P, Musil M, Weiperth A, Bláha M, Kubec J, Ruokonen TJ, Ercoli F, Bányai ZM, Buřič M, Veselý L, Kouba A. 2025. Seasonal changes in trophic ecology of co-occurring freshwater invasive species at a thermal locality. Hydrobiologia 852(17): 4493-4512. https://doi.org/10.1007/s10750-025-05872-8

Abstract

We investigated the trophic ecology of three non-native crayfish species (the marbled crayfish Procambarus virginalis, the red swamp crayfish Procambarus clarkii and the spiny-cheek crayfish Faxonius limosus) and two non-native fishes (the eastern mosquitofish Gambusia holbrooki and the three-spined stickleback Gasterosteus aculeatus) from two sections of a thermal tributary of the Barát brook in Budapest (Hungary) over the four seasons using carbon and nitrogen stable isotope analysis. All crayfish species occupied an omnivore trophic position in almost all sections and seasons. On the other hand, both fishes had a predatory trophic position, with G. aculeatus occupying a higher position than G. holbrooki. These patterns are confirmed by the results of the mixing models, showing spatial and temporal changes in the diet composition. We also found interspecific differences in the crayfish trophic niche in both sections during summer and overlapped niches in the other occasions, while fish had always segregated niches. Crayfish showed interseasonal differences in the trophic niche in both sections, while fish showed seasonal niche shifts only in the upper section. Our results show a considerable plasticity in the trophic ecology of the studied non-native populations, suggesting that the temperature variability gradient has no important role in determining their trophic niche. 

Keywords: Alien species • invasive species • stable isotopes • freshwater ecology • competition • predation

 

 

Art of invasive species

From Bluesky user charlie comes these art pieces of four invasive species, with Marmorkrebs in the middle:

 

 

The other three invasives are apple snails, round gobies, and European water chestnut plants.