Linzmaier and Jeschke, 2020

Linzmaier SM, Jeschke JM. 2020. Towards a mechanistic understanding of individual-level functional responses: Invasive crayfish as model organisms. Freshwater Biology 64(4): 657-673. https://doi.org/10.1111/fwb.13456

Abstract

1. In novel communities, a rising number of new and emerging invasive species interact with resident species, some of which are non‐native themselves. We implemented an innovative trophic interaction framework for novel communities and quantified the interaction strength and impact potential of a truly novel species (marbled crayfish Procambarus virginalis) with a resident non‐native counterpart (spiny‐cheek crayfish Faxonius limosus). As prey, we used Dreissena mussels, which are non‐native as well and now hold a key position in many European and North American aquatic ecosystems.
2. For both crayfish species, we predicted functional responses based on a mechanistic model that we parameterised with a set of experimental observations of foraging behaviour and satiation. We compared these predicted functional responses to empirically observed responses. In addition, we incorporated behavioural traits such as aggression, activity, and boldness in the comparisons between the species and individuals to determine their influence on functional responses. We tested individuals from aquarium stocks as well as naturalised individuals from invaded water bodies.
3. Altogether, we performed 1,095 experiments with 26 individual crayfish. We found that per capita predation of spiny‐cheek crayfish exceeded that of marbled crayfish from aquaria and naturalised individuals. Functional responses differed between species and were mostly higher for spiny‐cheek crayfish males. Marbled crayfish, however, were more voracious and reached satiation more slowly. Consumption rates correlated with aggression for marbled crayfish and with an aggressive threat response for spiny‐cheek crayfish.
4. We conclude that spiny‐cheek crayfish can reach higher short‐term consumption rates than marbled crayfish, but both species probably do not substantially affect Dreissena mussel populations in the field. For marbled crayfish, high long‐term consumption, interspecific aggression, and reproduction rates can promote their establishment and spread. Risk assessments of these invaders should be improved by considering numerical responses, and different prey organisms and predators.

Keywords: biological invasions • foraging • freshwater crayfish • functional response •  mechanistic model • predator–prey interactions • trait variation

Nature, nurture, noise

A new feature by Jordana Cepelewicz in Quanta Magazine starts off using marbled crayfish to make a point about variation:

In the 1990s, an army of clones invaded Germany. Within a decade, they had spread to Italy, Croatia, Slovakia, Hungary, Sweden, France, Japan and Madagascar — wreaking havoc in rivers and lakes, rice paddies and swamps; in waters warm and cold, acidic and basic. The culprits: six-inch-long, lobster-like creatures called marbled crayfish. ...

New research on crayfish and scores of other organisms is revealing an important role for a third, often-overlooked source of variation and diversity — a surprising foundation for what makes us unique that begins in the first days of an embryo’s development: random, intrinsic noise.

Marmorkrebs are not the point of the article, but it’s nice to see them so prominent featured. It’s a nice example of how marbled crayfish can be used as a model for general biological problems.

External links

Nature Versus Nurture? Add ‘Noise’ to the Debate.

Yonvitner and colleagues, 2020

Yonvitner Y, Patoka J, Yuliana E, Bohatá L, Tricarico E, Karella T, Kouba A, Reynolds JD. 2020. Enigmatic hotspot of crayfish diversity at risk: Invasive potential of non-indigenous crayfish if introduced to New Guinea. Aquatic Conservation: Marine and Freshwater Ecosystems 30(2): 219-224. https://onlinelibrary.wiley.com/doi/abs/10.1002/aqc.3276

Abstract

1. The large island of New Guinea has a rich indigenous astacofauna represented by numerous parastacids from the genus Cherax. The western half of the island is part of Indonesian territory.
2. Indonesia is known to be the main exporter of ornamental crayfish globally, and certain New Guinean species are exploited as ornamentals within the international pet trade. Moreover, one non‐indigenous species has been previously recorded being cultured in Java, Indonesia. This species, the North American Procambarus clarkii, is a vector of crayfish plague, the disease that is lethal to most parastacids. This population has already tested positive for the disease.
3. As the transport of non‐indigenous crayfish within the Indonesian territory is not restricted, their introduction to New Guinea can be expected. The Indonesian market was therefore surveyed for ornamental crayfish and their environmental suitability evaluated, as represented by temperature during the drought and rainy seasons in New Guinea.
4. Four North American and one Australian species were found advertised for sale. One of them, P. clarkii, was assessed as the most damaging species, followed by other North American species. A total ban on the culture and transport of the highest risk crayfish species in Indonesia and Papua New Guinea is recommended.

Keywords: Cambaridae • Cherax • climate matching • EICAT • Indonesia • MaxEnt • Parastacidae • pet trade • risk assessment

Hossain and colleagues, 2020

Hossain MS, Guo W, Martens A, Adámek Z, Kouba A, Buřič M. 2020. Potential of marbled crayfish Procambarus virginalis to supplant invasive Faxonius immunis. Aquatic Ecology: 54: 45-56. https://doi.org/10.1007/s10452-019-09725-0

Abstract

Biological invasions are a growing threat to global biodiversity due to negative impacts on native biota and ecosystem functioning. Research has expanded from investigating native and alien species interactions to examining relationships among alien species. Invasive crayfish may have similar life histories, niche preferences, and adaptation strategies, but their mutual interactions are little understood. This study aimed to quantify interaction patterns of size-matched calico crayfish Faxonius immunis, established in the Rhine River catchment, and the parthenogenetic marbled crayfish Procambarus virginalis, currently spreading throughout Europe. During agonistic interactions in the absence of shelter, marbled crayfish won a significant majority of fights against calico crayfish, but in the presence of shelter there was no significant difference. When sex of calico crayfish was considered in the analysis without shelter, marbled crayfish won a significantly higher number of fights with female calico crayfish. In the absence of shelter, marbled crayfish dominated calico crayfish females in 83.3% and males in 60% of pairs. With available shelter, the dominance of marbled crayfish was 100% and 54.5% over female and male calico crayfish, respectively. The results suggested that sex and resource availability influence agonistic behaviour in the studied crayfish. Marbled crayfish are confirmed to be competitive against the calico crayfish, which has been shown to be dominant over another serious invader in the Rhine River catchment, the spiny-cheek crayfish Faxonius limosus. In natural sympatric populations, the situation may be affected by factors such as size, reproductive variables, water temperature, and predation pressure.

Keywords: biological invasion • calico crayfish • competition • dominance • interaction • marbled crayfish

Tönges and colleagues, 2020

Tönges S, Masagounder K, Gutekunst J, Lohbeck J, Miller AK, Böhl F, Lyko F. 2020. Physiological properties and tailored feeds to support aquaculture of marbled crayfish in closed systems. bioRxiv: 2020.2002.2025.964114. https://doi.org/10.1101/2020.02.25.964114 (Unreviewed preprint)

Abstract

The marbled crayfish (Procambarus virginalis) is a new freshwater crayfish species, which reproduces by apomictic parthenogenesis, resulting in a monoclonal, all-female population. The animals have become a popular source for nutritional protein in Madagacar and are increasingly being considered for commercial aquaculture. However, their potential has remained unclear and there are also significant ecological concerns about their anthropogenic distribution. We show here that the size and weight of marbled crayfish is comparable to commonly farmed freshwater crayfish. Furthermore, purification of chitin from marbled crayfish shells revealed a high chitin content, which can be utilized for the synthesis of chitosan and other bioplastics. To allow the further evaluation of the animals in closed aquaculture systems, we used a factorial modeling approach and formulated tailored feeds that were matched to the marbled crayfish amino acid profile. These feeds showed superior performance in a feed trial, with a noticeable feed conversion rate of 1.4. In conclusion, our study provides important data for a balanced assessment of marbled crayfish as a new species for sustainable aquaculture and a feed that allows their culture in closed systems.

Keywords: None provided.

PhD position with Marmorkrebs

A doctoral position to study “Marbled crayfish as a model organism” is available! The position is in Czechia with Antonín Kouba. More information about the position are here.

Canadian province of Ontario asks for input on Marmorkrebs

Marmorkrebs may be added to Ontario’s invasive species list.

Several news outlets are reporting that the province’s Ministry of Natural Resources and Forestry is seeking public feedback concerning thirteen new species that might be added to the list.

Besides Marmorkrebs, the Louisiana red swamp crayfish (Procambarus clarkii) is another contender for regulation. If either was added, they would join one crayfish that is already regulated in Ontario, the Australian yabby (Cherax destructor).
 
A link to the Ontario government’s feedback page can be found here. The ministry says it will keep consultation open until 30 March 2020.

I highly recommend any crayfish biologists, particularly those with expertise in Marmorkrebs, complete the feedback form.

External links

Ontario taking action against invasive species
Province asking for feedback on invasive species
MNRF wants your opinion on 13 invasive species from wild pigs to red swamp crayfish
Province seeks input on 13 invasive species