Haubrock and colleagues, 2019

Haubrock PJ, Kubec J, Veselý L, Buřič M, Tricarico E, Kouba A. 2019. Water temperature as a hindrance, but not limiting factor for the survival of warm water invasive crayfish introduced in cold periods. Journal of Great Lakes Research 45(4): 788-794. https://doi.org/10.1016/j.jglr.2019.05.006

Abstract

The success of non-native species establishment depends on various abiotic and biotic factors that determine the outcome of an introduction event. Limiting temperature ranges have been studied for various non-native species; however, such previous assessments of species-specific temperature thresholds may be inadequate. Because several non-native crayfish species prefer warmer water temperatures, introductions were generally assumed to occur during preferable, warmer periods. However, despite the generality, traditionally considered ‘warm-water’ species are gradually appearing in new habitats, which were previously considered too cold for successful establishment. Newly discovered overwintering abilities of these species are likely related to the winter stratification in lentic ecosystems, which maintain tolerable conditions. To understand better the survivability of two such non-native species, red swamp crayfish Procambarus clarkii and marbled crayfish Procambarus virginalis individuals were abruptly subjected to a thermic shock which lowered the water temperature from 20°C (room temperature) to 6°C, 4°C and 2°C, thus mimicking the release by pet owners during various phases of winter. The survival rate and foraging activity were monitored for up to 98 days. Procambarus clarkii showed a considerable higher survival rate at low temperatures (4°C, 2°C) compared to that of P. virginalis with neither sex nor size differences evident. Our findings reveal the ability of warm water invaders to withstand a shock during introduction at low temperature periods without acclimation. Considering these newly discovered shifts in physiological limitations, particularly for the red swamp crayfish, this may indicate a higher threat for areas with colder conditions.

Keywords: mortality • pet trade • biological invasion • thermocline

Guo and colleagues, 2019

Guo W, Kubec J, Veselý L, Hossain MS, Buřič M, McClain R, Kouba A. 2019. High air humidity is sufficient for successful egg incubation and early post-embryonic development in the marbled crayfish (Procambarus virginalis). Freshwater Biology 64(9): 1603-1612. https://doi.org/10.1111/fwb.13357

Abstract

1. Severe weather events, such as long‐term droughts, are challenging for many freshwater species. To survive drought, freshwater crayfish tend to inhabit shelters or burrows where they can remain in contact with water or high humidity environments. However, it is not known whether embryogenesis or post‐embryonic development can occur without free standing water.
2. To address this question, three experiments were conducted using artificial burrows with high air humidity and using marbled crayfish (Procambarus virginalis Lyko, 2017) as a model species. Marbled crayfish are capable of parthenogenetic reproduction, burrow extensively and are able to travel long distances over land. In the first experiment, ovigerous females were transferred to simulated burrows without free water, but with high air humidity. A control group of females were kept in burrows with free water. Successful hatching was achieved in both groups.
3. In the second experiment, ovigerous females were transferred to simulated burrows with no free water but high air humidity and post‐embryonic development were observed. Following successful hatching, offspring moulted to the second developmental stage (stage 2 juveniles). Stage 2 juveniles remained viable without free water for 20 days, but further development was not observed. However, when some of these stage 2 juveniles were placed back into fully aquatic conditions (experiment 3), they moulted to stage 3 within 4 to 8 days.
4. These results demonstrated the ability of marbled crayfish to undergo terminal phases of embryogenesis, including hatching, as well as early post‐embryonic development under high air humidity conditions only. Post‐embryonic development was suspended in the absence of free water, and successfully resumed when re‐immersed.
5. This similar ability to tolerate drought‐like conditions during post‐embryonic development may also occur in other crayfish species, especially primary burrowers. This unprecedented life history trait may be crucial for inhabiting ecosystems with rapidly changing water regimes. In drying climates, it may confer advantages on some crayfish species (including some invasive species) over others.

Keywords: burrow • drought • hyporheic dweller • macroinvertebrate • ontogeny

Écrevisse marbrées en France

Marmorkrebs have been found in the wild in France. As of now, all I know is this tweet from Marc Collas:

The marbled crayfish (Procambarus virginalis) has just been discovered in France on the basin of the river Moselle. This is the first observation of this species in France #crayfish #ecrevisse #marmorkrebs #biodiversite

It is perhaps not surprising that Moselle River is the first location where Marmorkrebs have been found in France. The river borders Germany, which has been ground zero for Marmorkrebs introductions. It is a tributary for the Rhine River. It’s possible that the crayfish were introduced in Germany and spread into France.

More information as I learn it. The map of Marmorkrebs introductions has been updated accordingly.

External links

Marc Collas on Twitter
River Moselle

Hossain and colleagues, 2019c

Hossain MS, Kouba A Buřič M. 2019. Morphometry, size at maturity, and fecundity of marbled crayfish (Procambarus virginalis). Zoologischer Anzeiger 281: 68-75. https://doi.org/10.1016/j.jcz.2019.06.005

Abstract

Morphometric ratios, relationships and condition factors provide information regarding growth patterns, population dynamics and well-being of individuals in particular environments. Ecology of any species is then better understandable through life history traits and reproductive potential. The present study is aimed at exploring the morphometric and reproductive patterns of the parthenogenetic marbled crayfish, Procambarus virginalis. Marbled crayfish exhibited positive allometric growth and statistically significant common length-weight relationships. Abdomen width, claw length, width, and height increase significantly faster than the chosen most robust body size parameter, postorbital carapace length (POCL). Conversely, total length, carapace length, carapace width, and abdomen length grow proportionally slower than POCL. The condition factor was higher than the threshold value of ∼1 indicating the well-being of the crayfish used. Marbled crayfish, at their first reproduction, were recorded as long as 42.8 ± 10.8 (31.5–73.5) mm total length with a mean fecundity of 89.72 ± 56.9 (22–349) eggs. The relative fecundity (per 1 mm of POCL) of females reproducing for the first time was significantly lower compared to those reproducing repeatedly. Fecundity and relative fecundity exhibited a significant linear relationship with the carapace length and weight of mothers. As a tool for total fecundity estimation, the number of eggs on the third pair of pleopods was counted and plotted against size of mothers, and total fecundity. The number of eggs attached to the third pair of pleopods very closely correlates with the carapace length, weight and total fecundity. Based on our results, it can be concluded that abdomen width and claw growth is allometric compared to POCL which confirms the importance of these body parts. Fecundity parameters were confirmed to have a tight relationship to marbled crayfish size. Clutch size estimation can be used in future research based on the close correlation of egg counts on third pleopods and total fecundity.

Keywords: growth • reproduction • Procambarus virginalis • morphometry • fecundity

Weiperth and colleagues, 2019

Weiperth A, Gál B, Kuøíková P, Langrová I, Kouba A, Patoka J. 2019. Risk assessment of pet-traded decapod crustaceans in Hungary with evidence of Cherax quadricarinatus (von Martens, 1868) in the wild. North–Western Journal of Zoology 15(1): 42-47. http://biozoojournals.ro/nwjz/content/v15n1/nwjz_e171303_Weiperth.pdf

Abstract

The pet trade is one of the most important sources of introduction of freshwater non-native decapod crustaceans. Precise and timely identification of potentially hazardous species is necessary for the effective prevention of new introductions. Here, we present a list of species of ornamental freshwater decapod crustaceans pet-traded in Hungary and their risk assessment, including the probability of establishment based on climate matching. The list contains 13 shrimps, eight crayfish, two crabs, and one hermit crab. Three crayfish, Cherax destructor, Procambarus clarkii, P. virginalis, and one crab, Eriocheir sinensis, were classified in the high-risk category. During field sampling, we found three individuals of C. quadricarinatus that were probably released or escaped from aquaria. These are the first records of this species in the wild of Carpathian Basin. We strongly recommend further educating hobbyists about the risks related to the escapes and releases of high-risk taxa, as well as monitoring of the region for their occurrence.

Keywords: Carpathian Basin • crayfish • crab • hermit crab • invasiveness • ornamental animal • redclaw • shrimp

Vogt and colleagues, 2019

Vogt G, Dorn NJ, Pfeiffer M, Lukhaup C, Williams BW, Schulz R, Schrimpf A. 2019. The dimension of biological change caused by autotriploidy: A meta-analysis with triploid crayfish Procambarus virginalis and its diploid parent Procambarus fallax. Zoologischer Anzeiger 281: 53-67. https://doi.org/https://doi.org/10.1016/j.jcz.2019.06.006

Abstract

The biological changes caused by autotriploidy are poorly studied in animals. To investigate this issue in depth, we compared genetics, morphology, life history, ecology and behaviour of the triploid marbled crayfish and its diploid parent, slough crayfish Procambarus fallax. We performed a meta-analysis of our data and literature data. Our COI based molecular tree, consisting of 27 species of Cambaridae, confirmed the close taxonomic relationship between marbled crayfish and P. fallax. Comparison of both crayfish revealed similarities in mitochondrial gene sequences, morphological characters, colouration, body proportions and behaviours. Considerable differences were recorded with respect to chromosome number in somatic cells, haploid genome size, DNA methylation level, body size, fecundity, longevity, population size structure, invasiveness, and the range of inhabited biomes. These differences have dimensions that are otherwise only observed between species supporting earlier proposed raising of marbled crayfish from P. fallax forma virginalis to a new species named Procambarus virginalis. Particularly noteworthy is the enhancement of the fitness traits that probably resulted from evolutionary changes in gene expression. These alterations and the transition from sexual reproduction to parthenogenesis are likely responsible for the increased invasiveness of marbled crayfish in tropical to cold-temperate biomes.

Keywords: autopolyploidy • marbled crayfish • genetics • morphology • life history • ecology

Announcement: 23rd International Association of Astacology symposium

The 23rd International Association of Astacology symposium will be hosted the University of South Bohemia in the Czech Republic from June 29 to July 3, 2020.

The symposium will be held in Hotel Štekl, near the beautiful Hluboká nad Vltavou Château (pictured).

Planned topics including species diversity and distribution, conservation, physiology, genetics, ecology, ethology, diseases, fishery and aquaculture.

In addition to the scientific program, events will include trips to the experimental facilities of the University of South Bohemia, natural crayfish locality in the Šumava National Park, the Hluboká nad Vltavou Château, beer tasting with the Budweiser Budvar Brewery, the Český Krumlov UNESCO Heritage castle, and wooden rafting.

Abstract submission runs from 1 December 2019 to 15 April 2020.

Early registration deadline: 31 March 2020
Regular registration: 30 April 2020Late registration: 31 May 2020

External links

23rd Symposium of the International Association of Astacology