Balzani and colleagues 2025

Balzani P, Musil M, Weiperth A, Bláha M, Kubec J, Ruokonen TJ, Ercoli F, Bányai ZM, Buřič M, Veselý L, Kouba A. 2025. Seasonal changes in trophic ecology of co-occurring freshwater invasive species at a thermal locality. Hydrobiologia 852(17): 4493-4512. https://doi.org/10.1007/s10750-025-05872-8

Abstract

We investigated the trophic ecology of three non-native crayfish species (the marbled crayfish Procambarus virginalis, the red swamp crayfish Procambarus clarkii and the spiny-cheek crayfish Faxonius limosus) and two non-native fishes (the eastern mosquitofish Gambusia holbrooki and the three-spined stickleback Gasterosteus aculeatus) from two sections of a thermal tributary of the Barát brook in Budapest (Hungary) over the four seasons using carbon and nitrogen stable isotope analysis. All crayfish species occupied an omnivore trophic position in almost all sections and seasons. On the other hand, both fishes had a predatory trophic position, with G. aculeatus occupying a higher position than G. holbrooki. These patterns are confirmed by the results of the mixing models, showing spatial and temporal changes in the diet composition. We also found interspecific differences in the crayfish trophic niche in both sections during summer and overlapped niches in the other occasions, while fish had always segregated niches. Crayfish showed interseasonal differences in the trophic niche in both sections, while fish showed seasonal niche shifts only in the upper section. Our results show a considerable plasticity in the trophic ecology of the studied non-native populations, suggesting that the temperature variability gradient has no important role in determining their trophic niche. 

Keywords: Alien species • invasive species • stable isotopes • freshwater ecology • competition • predation

 

 

Art of invasive species

From Bluesky user charlie comes these art pieces of four invasive species, with Marmorkrebs in the middle:

 

 

The other three invasives are apple snails, round gobies, and European water chestnut plants.

Marin and colleagues, 2025

Marin IN, Statkevich SV. 2025. The first discovery of the invasive marbled crayfish Procambarus fallax (Hagen, 1870) in Crimea. Arthropoda Selecta 34(3): 359–364. https://kmkjournals.com/journals/AS/AS_Index_Volumes/AS_34/AS_34_3_359_364

Abstract

Data on the discovery of the invasive marbled crayfish Procambarus fallax (Hagen, 1870) (Decapoda: Cambaridae) in the western Crimea, in the lower streams of the Alma and Belbek rivers, is presented. This is the first report of its presence on the peninsula, adding another invasive species to the list in the Russian Federation. Phylogenetic analysis reveals that the crayfish found in Crimea share the same genetic haplotype as other invasive subpopulations from Europe, Sweden, Japan, and parts of Florida. The European subpopulation has a single haplotype, suggesting a relatively recent introduction, likely from a single parent within its native range in Florida. In the case of the lower reaches of the Alma and Belbek rivers, we propose a hypothesis based on the possible involvement of large migratory birds, such as hissing swans and ducks, and plants attached to their paws in the spread of juvenile crayfish to nearby water reservoirs.

Keywords: invasion • Decapoda • Crustacea • crayfish • COI mtDNA • Crimean Peninsula

Toutain and colleagues 2025

Toutain M, Soto I, Oficialdegui FJ, Balzani P, Cuthbert RN, Huber AF, Haubrock PJ, Kouba A. 2025. Claw loss and the prey preferences of an invasive crayfish. NeoBiota 100: 91-108. https://doi.org/10.3897/neobiota.100.149248

 

Abstract

 

Predator-prey relationships underpin the stability of ecosystems but can be perturbed by numerous factors, such as biological invasions. Crayfish readily colonize new ecosystems and their impacts can modify food webs or ecosystem functioning. However, while crayfish exert high levels of predation pressure handling prey with their claws, claw loss is also common in their populations, which could mediate prey selection pressures. Here, we investigate how the number of claws in the marbled crayfish Procambarus virginalis modulates its preferences for two different available prey: Chironomus plumosus and Gammarus fossarum. We showed that the food preference of P. virginalis was mainly for soft, less mobile prey, such as C. plumosus, with significantly fewer G. fossarum (harder, more mobile prey) being killed. This preference was largely independent of claw presence but depended on the availability of prey, with fewer G. fossarum being targeted as the number of claws decreased. Our results highlight the complexity of predator-prey ecological relationships in invaded freshwater ecosystems and show that some biotic factors, such as the quantity and type of prey available, need to be taken into account in order to better understand their role in ecosystem dynamics.

Keywords: Chironomus plumosus • choice experiment • feeding preference • Gammarus fossarum • macroinvertebrate community • prey preference • Procambarus virginalis 

 

Ložek and colleagues 2025

Ložek F, Staňová AV. 2025. Conjoined twins in marbled crayfish Procambarus virginalis Lyko, 2017 (Decapoda: Astacidea: Cambaridae). Journal of Crustacean Biology 45(2): ruaf033. https://doi.org/10.1093/jcbiol/ruaf033 

Abstract

We report the first observation of viable conjoined twins of marbled crayfish Procambarus virginalis Lyko, 2015 during postembryonal development. Two cases of hatched juveniles were identified incidentally among normal hatchlings from eggs of laboratory-stocked marbled crayfish during an experiment unrelated to the observation. In the first case, each twin had its own anteroposterior body axis with dorsal adhesion in the cephalothorax region, referring to conjoined twins pattern duplicitas completa. They lived for 37 days post-hatch in the laboratory and survived moulting into the third postembryonal stage. The second case involved conjoined twins with unequal-sized embryos that died before the first moulting. Despite the rarity of the observation, the two cases occurred close in time and among a relatively low number of eggs, suggesting that the frequency of conjoined twins should be experimentally verified, as marbled crayfish could represent a promising model for its study.

 

Keywords: None provided. 

Kronenberger and colleagues 2025

Kronenberger JA, Wilcox TM, Schwartz MK. 2025. SmartScreen-AIS: A high-throughput qPCR chip for nationwide surveillance of aquatic invasive species. Environmental DNA 7(3): e70144. https://onlinelibrary.wiley.com/doi/abs/10.1002/edn3.70144

Abstract

 

Effective wildlife conservation requires frequent and widespread data on species occurrence. With the maturation of eDNA-based monitoring—now widely recognized as sensitive, cost effective, and legally defensible—nationally coordinated eDNA strategies are beginning to take shape. Such ambitious initiatives will require eDNA analytics with the throughput and sensitivity required for surveillance of many protected, pathogenic, and invasive species across broad geographic scales. Here, we help meet this need with SmartScreen-AIS: a high-throughput qPCR (HT-qPCR) chip with 46 assays targeting aquatic invasive species of widespread concern. SmartScreen-AIS was validated for use throughout the continental United States and can be subdivided into smaller chip formats as desired for use in specific regions or biomes. Assay performance in HT-qPCR was strong relative to conventional qPCR, with slightly lower specificity in some cases (due to pre-amplification) but significantly higher sensitivity. Contamination was rare, PCR inhibition was minimal to nonexistent, and demonstration at three military installations detected eDNA from all species on the chip that were known to be present and one species that was previously undocumented. Cost savings will depend on the number of assays used and samples tested, but in this study we estimate that eDNA analyses were 75% cheaper using HT-qPCR than they would be with our conventional qPCR protocol. To facilitate use, we provide appendices with assay details, bench protocols, a script for processing results, and an online app with state-level assay specificity information. SmartScreen-AIS has the potential to advance early detection of invasive species in the United States, and we hope our HT-qPCR workflow inspires chip development and use globally.

 

Keywords: None provided.

 

Keywords: 

Teesalu and colleages 2025

Teesalu P, Muuga JM, Hurt M, Kaldre K, Nõges T, Ercoli F. 2025. Effects of temperature on marbled crayfish (Procambarus virginalis, Lyko 2017) invasion ecology. Hydrobiologia: 852: 3541–3558. https://doi.org/10.1007/s10750-025-05828-y

Abstract

 

The marbled crayfish (Procambarus virginalis) is an invasive freshwater species spreading across Europe. Understanding its establishment and distribution is crucial, particularly in relation to temperature. This study examined the role of water temperature in marbled crayfish invasion in a warm outflow channel of a power plant in Estonia. We hypothesized that warmer water temperatures and the temperature gradient along the channel would influence crayfish establishment, distribution, and trophic niche. Temperature loggers revealed a distinct gradient, with the channel being warmer than the adjacent reservoir, providing a more suitable habitat for crayfish. Stable isotope analysis (¹³C and ¹⁵N) with MixSIAR and SIBER models showed distinct trophic niches along the channel: crayfish at the head of the channel consumed macroinvertebrates and macrophytes, while those at the mouth mainly consumed macroinvertebrates and periphyton. Additionally, crayfish shifted from eating primary consumers in spring and summer to primary producers in autumn. Water temperature was a key factor in crayfish establishment, but food availability also likely influenced their distribution. This study highlights the role of water temperature and ecological factors in the invasion dynamics of marbled crayfish, especially in the context of global warming.

 

Keywords: Stable isotopes • trophic niche • invasive species • population dynamic • temperature effect