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.