Eiler A, Stensrud E, Osman O. 2025. Detection of marbled crayfish Procambarus fallax. protocols.io. https://dx.doi.org/10.17504/protocols.io.q26g78199lwz/v1
Abstract
Taqman QPCR assay for marbled crayfish Procambarus fallax.
Keywords: None provided.
05 February 2025
30 January 2025
The Crayfish Almanac
Don’t know how I missed this last year, but Michigan State University released Great Lakes Almanac to Invasive Crayfish.
It has one of the best short identification guides for Marmorkrebs I’ve seen. Click to enlarge!
Marbled crayfish (or marmokrebs) originated in the aquarium trade and are often called the self-cloning crayfish. All marbled crayfish are female and the offspring are clones. This species is of high concern because a single individual can produce an entire population in a short time.
This species has a distinct marbling pattern, but other species may look similar. Male crayfish with this pattern are not marbled crayfish.
To determine if its a female, look for a round pocket-like feature located on the underside between the last pair of walking legs. This is the sperm pouch (called an ‘annulus ventralis’) .
External links
24 January 2025
Golubev and colleagues 2024b
Golubev AP, Ulashchyk EA, Bodilovskaya OA. 2024. Modeling the growth of the invasive river crayfish species Procambarus virginalis (Decapoda, Astacidea) under different temperature conditions. https://www.researchgate.net/publication/387918897_Modeling_the_growth_of_the_invasive_river_crayfish_species_Procambarus_virginalis_Decapoda_Astacidea_under_different_temperature_conditions
Abstract
In
the marbled crayfish Procambarus virginalis, the dependence of the
duration of inter-larval intervals on body weight and the magnitude of
body weight gains for individual inter-larval intervals in the
temperature ranges 15.3–17.9 °С, 7.5–18.9, 19.1–20.8, 21.0–22.8,
22.9–25.2 and 25.3–28.9 °С was determined. The growth curves of
individuals in these temperature ranges and the sum of effective
temperatures (Sef) of individuals during juvenile growth and breeding
periods were calculated from these data. The average Sef value for the
juvenile period of P. virginalis (until newborn individuals reach a body
weight of 1.4 g) in the studied temperature ranges is 4316 degree·days
at the biological zero temperature of 7.6 °C. For the breeding period
(until reaching the body weight from 1.4 g to the limit weight of 15 g) –
respectively 10630 degree·days and 3.0 °C. Based on the annual dynamics
of mean monthly temperatures in six continental water bodies within the
invasive range of P. virginalis (Sweden, Belarus, Germany, Slovakia,
North Macedonia and Malawi), Sef values were calculated for the periods
of the year during which juvenile growth and reproduction of sexually
mature individuals are possible. In temperate water bodies located in
Sweden, Belarus, Germany and Slovakia, Sef values during the juvenile
growth period vary between 1083 and 2099 degree·days. In the more
southern body of water in Northern Macedonia, this value reaches 2990
degree·days, and in the tropical African body of water in Malawi it
reaches 7076 degree·days. Consequently, newborn individuals of P.
virginalis, which in water bodies of the temperate zone of Europe hatch
in the first half of summer, can reach sexual maturity only in the third
summer of life, and in a tropical water body – already in the first
summer of life. Sef values for periods of the year favorable for the
growth of sexually mature individuals in the studied water bodies of
Europe increase from 2031 degree·days (water body in Sweden) to 4657
degree·days (water body in Northern Macedonia). In the tropical water
body of Malawi, this figure reaches 8058 degree·days, i.e. the maximum
life span of P. virginalis in this water body does not exceed two years.
Nevertheless, throughout the entire range, sexually mature individuals
of P. virginalis are capable of producing no more than 2–5 clutches of
eggs per life cycle.
Note: The ResearchGate page includes a link to the DOI 10.46646/2521-683X/2024-4-18-34. At the time of this writing in January 2025, this link is not working. I will update this entry with more information if I learn more.
Golubev and colleagues 2024a
Abstract
The experiment examined the effect of temperature on the parameters of reproduction and growth in female marbled crayfish. At temperatures close to 20 °C, females began to reproduce at 10–11 months with a body weight of 0.84–1.20 g, but up to 80 % of their egg clutches were nonviable. The duration of egg embryogenesis with an increase in temperature from 16–17 to 26–27 °C decreased from 66–69 days to 21–24 days with a lower temperature development threshold equal to 13.1 °C. A similar molting value that determined the growth rate of individuals in juveniles weighing up to 0.34 g was 13–14 °C, but in sexually mature females it decreased to 5 °C. In water bodies of the temperate zone with a short growing season, females were able to reach sexual maturity only in the third summer of life and produced no more than two clutches of eggs during their life cycle. Hence, the invasive potential of marbled crayfish in the temperate zone of Europe is very limited.
Аннотация
В эксперименте исследовано воздействие температуры на параметры размножения и роста у самок мраморного рака. При температурах, близких к 20 °С, самки начинали размножаться в возрасте 10–11 месяцев при массе тела 0,84–1,20 г, однако до 80 % их кладок яиц были нежизнеспособными. Длительность эмбриогенеза яиц при повышении температуры от 16–17 до 26–27 °С снижалась от 66–69 до 21–24 суток при нижнем температурном пороге развития, равном 13,1 °С. Аналогичный показатель для частоты линек, которая определяет скорость роста особей, у молоди массой до 0,34 г составлял 13–14 °С, но у половозрелых самок он снижается до 5 °С. В водоемах умеренной зоны с коротким сезоном вегетации самки способны достичь половой зрелости лишь на третье лето жизни и произвести за жизненный цикл не более двух кладок яиц. Отсюда инвазивный потенциал мраморного рака в умеренной зоне Европы весьма ограничен.
17 January 2025
Garcia and colleagues, 2024
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Abstract
While previous studies have explored the impact of behavior and life history on environmental DNA (eDNA), little research has been conducted on the impact of molting on eDNA detectability and particle size for aquatic arthropods like crayfish. To address this knowledge gap, we conducted a study examining how molting affects eDNA detectability over a range of particle sizes using marbled crayfish (Procambarus virginalis Lyko, 2017). We collected water samples from aquariums at pre- and post-molt time intervals and filtered our samples using sequential filtration from large to small filter pore sizes. We found that molting had a weak negative effect on eDNA detectability, and P. virginalis eDNA was most detectable throughout the study at our largest filter pore size (5.0 µm) regardless of molt status. Additionally, time spent in aquariums had a strong, positive effect on eDNA detectability for P. virginalis. Given that molting had a weak effect on eDNA detectability for our study crayfish, we suggest that researchers align their sampling efforts with other seasonal life history events, like reproduction or egg extrusion, that have been demonstrated to improve eDNA detectability.
Keywords: None provided.
31 December 2024
2024 was a decent year for Marmorkrebs research
It’s time for our annual* tradition to look at the trendlines for marbled crayfish research...
I can’t say that I am super excited by what seems to be a new normal for Marmorkrebs research. There is a stronger need for research than ever, given that the number of countries with introduced Marmorkrebs just keeps growing. South Korea was added to the map of countries with confirmed introductions (although the discovery was a while back).
Meanwhile, Minnesota banned Marmorkrebs. And I am concerned that these bans are not having any exemptions for bona fide scientific research.
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 research2021 was the third best year ever for Marmorkrebs research
2022 was a slow year for Marmorkrebs research
* Except 2023. Sorry. Missed that one.
22 December 2024
Kamburska and colleagues 2024
Kamburska L, Sabatino R, Schiavetta D, De Santis V, Ferrari E, Mor J-R, Zaupa S, Garzoli L, Boggero A. 2024. A new misleading colour morph: is Marmorkrebs the only “marbled” crayfish? BioInvasions Records 13(4): 949-961. https://doi.org/10.3391/bir.2024.13.4.09
Abstract
We describe the occurrence of two unusually coloured crayfish individuals in two different locations in northwestern Italy (lakes Orta and Comabbio). They represent the first record in Italy of a marbled colour morph of Procambarus clarkii. Species assignment through morphological analyses was confirmed by molecular identification. Different body parts from the adult marbled coloured male and female, together with eggs and juveniles were analysed and blasted in GeneBank. All the sequences
were identified as P. clarkii, with a query coverage ≥ 99.0% and a percentage identity ≥ 99.7%. Based solely on external appearance, this new morphotype may lead to misinterpretation of taxonomic identification, being this colour morph very similar to the Marmorkrebs P. virginalis. A marbled female of P. clarkii could be wrongly attributed to Marmorkrebs when identification keys and molecular taxonomy are not considered to complement each other. The marbled morph of P. clarkii not only illustrates how varicoloured are the members of the family Cambaridae, but it also suggests that marbled colour alone is inadequate to identify a species. Therefore, it is recommended to consider this new colour in the morphological identification of the adult red swamp crayfish P. clarkii. The approach that integrates both molecular and morphological information improves promptly species taxonomy towards timely and appropriate management measures.
Keywords: DNA barcoding • integrative taxonomy • morphological analyses • morphotype • phenotypic plasticity • red swamp crayfish
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