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

2022 was a slow year for Marmorkrebs research

 This is usually a more optimistic exercise for me.

After years of being able to write that “This was the best year ever,” the last five years show a downward trend in the number of research publications on Marmorkrebs. This graph shows only journal articles, and excludes one interesting article in Crayfish News. Still, even if I included that, this is the least active year in 6 or 7 years.

This may be because some of the original research questions about Marmorkrebs – their origin and basic biology – are now resolved. It may also be that because this species is more widespread, new records of introductions are less likely to be reported or published.

The biggest story this year was the expanding use of local legislation to ban or regulate the sale of Marmorkrebs in the pet trade. Someone was actually charged under a law for selling Marmorkrebs for the first time. Ontario and Georgia banned Marmorkrebs, and Minnesota is thinking about it.The Ontario ban is quite significant, given the size and population of the province.

 

Previous year end reviews

2008 was the best year ever for Marmorkrebs research

2009 was tied for the best year ever in Marmorkrebs research

2010 was the best year ever for Marmorkrebs research

2011 was not the best year ever for Marmorkrebs research

2012 was an average year for Marmorkrebs research

2013 was the second best year ever for Marmorkrebs research

2014 was a good year for Marmorkrebs research

2015 was the best year ever for Marmorkrebs research

2016 was the best year ever for Marmorkrebs research

2017 was the second best year ever for Marmorkrebs research

2018 was the second best year ever for Marmorkrebs research

2019 was the second best year ever for Marmorkrebs research

2020 was not the best year for Marmorkrebs research

2021 was the third best year ever for Marmorkrebs research

 

Georgia bans Marmorkrebs

The One Green Planet site is reporting that the southern US state of Georgia has announced plans to ban Marmorkrebs.

 

The ban would take effect 4 December 2022. A perusal of a public announcement from the Georgia Department of Natural Resources (PDF) seems to show that keeping almost any other crayfish species – except Louisiana red swamp crayfish (Procambarus clarkii) and White river crayfish (Procambarus zonangulus) – would require a permit.

 

The state and provincial regulations seem to be picking up steam. But I continue to worry about whether these bans are taking into account that there might be researchers who might want to study these animals for scientific purposes.

External links

Georgia Department of Natural Resources Subject 391-4-8 Wild Animals (PDF)

Georgia finally expands restrictions on wild animals as pets

Map by TUBS - This SVG locator map includes elements that have been taken or adapted from this locator map:, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=15948353

Minnesota eyes Marmorkrebs ban

 Read the story here.

Gallardo and colleagues, 2022

Gallardo B, Sutherland WJ, Martin P, Aldridge DC. 2022. Applying Fault Tree Analysis to biological invasions identifies optimal targets for effective biosecurity. Journal of Applied Ecology 59(10): 2553-2566. https://doi.org/10.1111/1365-2664.14256

 

Abstract

 

1. The management of invasive species requires analytical tools that can synthesise the increasing and complex information generated through risk assessment protocols. To that end, fault tree analysis (FTA) provides a means to conceptually map all of the events leading to a particular undesired scenario with associated probabilities and uncertainty.
2. We used a peer-reviewed dataset (the GB Non-Native Species Risk Assessments) to build and quantify a FT of all the events leading to the transport, introduction, establishment and spread of harmful aquatic invasive species in Great Britain. We also simulated management scenarios.
3. Individual barriers to invasion, either natural or human, were largely unsuccessful in hindering invasion (42%–91% probability of failure in a 5-year period); yet the high interdependence of events in the tree resulted in an overall probability of harmful invasion of about 3%. This figure is much greater than that estimated by the tens rule, which posits that 10% of non-native species manage to colonise a new area, and only 10% of those become invasive, resulting in a 1% overall probability of harmful invasion.
4. We used the FTA to explore different management intervention scenarios and found that pre-border management reduced the overall risk of invasion by 86%, followed in importance by early action after introduction (85%), and detection at the border (81%). In contrast, post-establishment management techniques, such as eradication and containment, had a limited impact reducing the probability of widespread invasion (18%–24%).
5. Synthesis and applications. While prevention has been long recognised as the most cost-effective action against biological invasions, here we were able to quantify the reduction in invasion risk under a range of management scenarios. Optimising all management elements included in the FT reduced the overall probability of invasion by three orders of magnitude.
6. We conclude that FTA provides a baseline to capitalise on a growing source of peer-reviewed risk assessments, which allows systematic assessment of the effectiveness of future actions to prevent and manage invasive species at the national and international levels. The analytical framework can be extended to other biological threats (e.g. pests, pathogens, diseases) and scenarios (e.g. climate change, war), so that breach and leverage points in biosecurity can be identified.

 Keywords: None provided.

Dobrović and colleagues, 2022

Dobrović A, Geček S, Klanjšček T, Haberle I, Dragičević P, Pavić D, Petelinec A, Boštjančić LL, Bonassin L, Theissinger K, Hudina S. 2022. Recurring infection by crayfish plague pathogen only marginally affects survival and growth of marbled crayfish. NeoBiota 77: 155-177. https://doi.org/10.3897/neobiota.77.87474

 

Abstract

 

Invasive alien crayfish threaten the diversity of freshwater ecosystems and native crayfish fauna. In Europe, this is largely due to transmission of the crayfish plague to susceptible native crayfish. Many invasive species tolerate crayfish plague, but the infection still has the potential to reduce the fitness of a tolerant host due to energy trade-offs between immune response maintenance and life-history traits, such as growth and reproduction. In combination with other unfavourable conditions, such a response could alter further invasion success of an otherwise successful crayfish invader. We examined whether repeated infection with one of the most virulent haplogroups of crayfish plague agent (Aphanomyces astaci) affects growth or survival of the juvenile marbled crayfish (Procambarus virginalis). Juveniles were exposed to i) two levels of pathogen concentrations, and ii) two different feeding regimes under the higher pathogen concentration. In all performed trials, repeated infection reduced growth rates, while the combination of recurring infection and food limitation significantly increased mortality. The average energy cost of the immune response was estimated at 12.07 J/day for individuals weighing 0.3 grams. Since infections were frequent and pathogen concentrations high, results suggest that marbled crayfish is resistant to A. astaci pathogen and its survival is only affected by adding the stress of food limitation. The survival of almost half of the individuals exposed to high pathogen loads and extreme food limitation indicates that chronic infection by crayfish plague is unlikely to be an important factor impeding invasion success of the marbled crayfish, even under harsh conditions. Our results add to the growing body of evidence that marbled crayfish has potential to become one of the most successful freshwater invaders.

 

Keywords: food limitation • freshwater • immunity cost • infection • invasive species • trade-off