Abstracts

IAA24 Book of Abstracts (PDF)

Meeting Program/Schedule (PDF)

 

 VIEW MEETING PROGRAM ONLINE

 

 

LIST OF MEETING ABSTRACTS

NOTE: You may quickly navigate to a name you are looking for by clicking a letter below (first letter in their lastname).

Oral | Posters

Oral Presentations

 

 

Day: 3, Session: 2, Talk: 2

Spatio-temporal Occurrence and Abundance of Faxonius limosus (Decapoda: Cambaridae) in Two North-western Subalpine Lakes (Italy)

ORLANDI M, Schiavetta D, Kamburska L, Zaupa S and Boggero A

Biological invasions are among the most influential human-driven processes impacting Earth’s ecosystems, with freshwaters being particularly vulnerable as transition ecosystems. Invasive crayfish impact substantially these environments and their ecosystem services. Lakes Orta and Mergozzo are two subalpine lakes (NW Italy) where the invasive American crayfish Faxonius limosus is well established. The current study examined the population structure, and its temporal and spatial distribution over a one-year period (2021-2022). Monthly littoral trap samples (taken in the same week in both lakes) enabled us to measure, weigh, and sex-determine all gathered individuals and asses their relative abundance measured as Catch Per Unit Effort (CPUE; number of crayfish per trap per trapping night). The population structure was then examined to determine: 1) the invasive species' abundance, 2) size variation between the two lakes, and 3) the invasive species' potential use as waste reduction strategy by producing biofilm for sustainable food packaging. The total number of individuals were higher in Lake Orta (86) than in Lake Mergozzo (57) and dominated by males (sex ratio M/F of 1.39 and 3.07, respectively). Average abundance was comparable between the two lakes, but species size distribution was greater in Lake Mergozzo than in Lake Orta. Crayfish-derived film shows higher melting temperatures, mechanical resistance and slower degradation than the commercial plastic one. Therefore, producing crayfish-based biofilm from shell-derived chitosan from F. limosus may be a practical strategy for waste reduction as its crayfish-derived film is qualified to be introduced into the commercial market, at least in countries where their use is legal since they are native. Our research also contributes significantly to the understanding of the ecology of F. limosus in deep lakes.

 

 

Day: 5, Session: 2, Talk: 1

Exploring the Evolution of Aphanomyces: Were Ancestral Oomycetes Such Effective Parasites?

ORTEGA LÓPEZ P, Sandoval-Sierra V and Diéguez Uribeondo J

Saprolegniales (Oomycetes) are a group of oomycetes that comprises plant and animal parasites and also saprotrophs. While extensive research has explored the devastating impact of plant parasitic oomycetes, particularly within Saprolegniales, limited knowledge exists regarding the evolution of lifestyles within this group. This study focuses on understanding the patterns and rates of evolution and diversification of saprotrophic and parasitic lifestyles, with a specific emphasis on the genus Aphanomyces, which includes the crayfish plague disease agent A. astaci. In order to study patterns and rates of the evolution and diversification of the saprotrophic and parasitic lifestyles, we have performed comparative phylogenetic analyses (Bayesian inference and Maximum likelihood) on 2950 bp nuclear internal transcribed spacer (ITS) ribosomal DNA sequence database, using all information available in the GenBank plus the one generated by our group. The results indicated that in the Saprolegniales there is a strong phylogenetic signal for the trait lifestyle (saprotrophic, animal and plant parasitic), meaning that the distribution of this trait is closely associated with the evolutionary history and phylogenetic relationships of the species. Our results show that ancestral oomycetes were parasites, most likely infecting plants, while the saprotrophic lifestyle seem to be a derived character that evolved later. In addition, the acquisition of the saprotrophic lifestyle appears to be first adopted by ancestral Saprolegniales species. However, plant parasitism in the Saprolegniales was lost until recent innovations acquired during events of diversification of the genus Aphanomyces (?50 Mys).

 

Poster Presentations

 

 

POSTER 1

Molecular Diagnostic Method for Detection of Nosema austropotamobii (Microsporidia) in White-clawed Crayfish

BASSO A, Paolini V, Fea G, Ghia D and Pretto T

Microsporidia are obligate intracellular pathogens that infect a wide range of invertebrate and vertebrate hosts, often resulting in chronic disease. In the white-clawed crayfish (Austropotamobius pallipes complex), the most studied microsporidia are Astathelohania contejeani and Nosema austropotamobii, which cause the "porcelain disease"", characterized by a typical whitish appearance of the abdominal tissues. Recent publications have highlighted that A. contejeani and N. austropotamobii can circulate within the same population and sometimes co-infect the same crayfish. Currently, specific molecular identification methods are available only for A. contejeani, while the detection of N. austropotamobii relies on generic molecular protocols, mainly based on the SSU rRNA. Although this gene commonly offers sensitivity advantages, its high conservation and repeat motifs complicate species-specific assays. Therefore, it is crucial to design molecular methods to detect N. austropotamobii based on other genetic regions to ensure specificity and avoid cross-reactions with other microsporidia or similar microorganisms. For this purpose, we selected the RNA polymerase II largest subunit (RPB1) gene because it exhibits enough variability among these organisms. The newly developed end-point PCR was verified and validated using more than 40 A. pallipes specimens previously evaluated with the published molecular protocols for microsporidia. The new method produces a single amplicon of about 400 bp in N. austropotamobii-affected specimens without amplification from A. contejeani-infected or microsporidia-negative samples. All amplicons were sequenced and compared with sequences available in the NCBI database, showing >99% similarity to N. austropotamobii-RPB1 gene, corroborating the specificity and reliability of this new protocol."

 

 

POSTER 2

Tracking Signal Crayfish During the Cold Season in Lake Vättern with Acoustic Telemetry

BOHMAN P, Palm D and Berger D

This ongoing study gives indications that crayfish movements could be successfully tracked during the cold season using acoustic telemetry. Our aim was to investigate how the accuracy of triangulation changed with the distance to the receiver and when the signal was obscured by artificial burrows. The invasive signal crayfish is abundant in Lake Vättern and is active during the cold season. It could therefore affect sensitive species and environments all year round, e.g. aggregations at spawning sites of arctic char in October and migrations to deeper, possibly more sensitive areas during autumn and winter. We investigated how to use externally attached transmitters on crayfish carapace both in the laboratory and in the field. Our results did not indicate higher mortality as a consequence of the external tags. In the field we tested different sized transmitters with various power output both on crayfish in constructed burrows and out in the open. We tested tags with both fast (20 sec) and slower (180 sec) signals. Despite signal differences we were able to acceptably triangulate the crayfish. As the experiment is ongoing, we will be able to test a more thorough and more accurate triangulation in the near future. In our follow-up experiment we will test tags with longer delays and also fewer of the fixed 20 second tags (fewer tags pinging simultaneously) which we believe will cause less signal collision.

 

 

POSTER 3

Updated Distribution and Characterization of Crayfish Plague and Microsporidiosis Affecting Austropotamobius pallipes complex in Trentino (Northeast Italy)

BRUNO MC, Basso A, Endrizzi S, Paolini V and Pretto T

One of the causes of the decline in distribution and abundance of the endangered white-clawed crayfish Austropotamobius pallipes complex throughout Europe is the widespread invasion of alien crayfish and the associated spread of infectious diseases, primarily crayfish plague caused by Aphanomyces astaci. Although this disease usually causes mass mortality in A. pallipes, some wild populations appear tolerant towards A. astaci. Another relevant disease is microsporidiosis (porcelain disease), caused by the parasites Astathelohania contejeani and/or Nosema austropotamobii. In 2021-2024, we conducted a monitoring survey, aimed at mapping the distribution of A. astaci, A. contejeani and N. austropotamobii in wild populations of A. pallipes in Trentino (Northeast Italy). We applied non-invasive sampling methods to collect cuticular swabs from 31 of the 46 known populations, investigate the presence of A. astaci and if possible, identify its genotype through molecular analyses. Aphanomyces astaci was detected in 8 populations, and the presence of a low pathogenic genotype (genotype A) was confirmed in one of them. Thirty-three specimens from 10 populations showed macroscopic signs of porcelain disease, abdominal muscle tissues were collected and subjected to molecular evaluation. The presence of A. contejeani was identified in 23 individuals from 9 populations and N. austropotamobii was detected in 3 individuals, from 3 populations. Eight specimens collected from 6 populations were co-infected by the two microsporidians.

 

 

POSTER 4

There Can be Only One: The Two-year Spread of Procambarus clarkii in a Faxonius limosus Infested Small Perialpine Lake in Trentino (Northeast Italy)

BRUNO MC, Burgio S, Conti A and Marcellucci C

A containment campaign to prevent the spread of Faxonius limosus was conducted in June, July and September 2023 and repeated in 2024, in Costa Lake, a Special Area of Conservation of about 1 hectare surface area, where this IAS was first recorded in spring 2021. Unexpectedly, in June 2023 we trapped 38 adult Procambarus clarkii in the NW part of the lake, suggesting a recent point of introduction. Procambarus clarkii showed a high invasive potential, spreading quickly in 2023 to the whole lake perimeter and its emissary canal; its body size was much larger than that of F. limosus, with two main size classes, one (50-60 mm cephalothorax length) corresponding to the individuals introduced most likely in the fall 2022 (2-years old), and a second class (40-50 mm) representing the new generation born in the lake. In July 2024, we recorded three main size classes: about half of the P. clarkii population belonged to the 50-60 mm size class (2-years old), while the remaining was evenly distributed between the size classes of 40-50 mm (new generation) and 60-70 mm, i.e., older individuals (4-years old). F. limosus did not show significant shifts in size: in both years the majority of the individuals belonged to the 30-40 mm size class. The much larger size of P. clarkii, longer time span, fast dispersion ability, suggest a future dominance of P. clarkii and possible disappearance of F. limosus, with relevant risk of spread of this new, more invasive species to the upstream, hydrologically connected, water bodies. This study was partly supported by the EU LIFE Programme: LIFE-CLAW, Crayfish Lineages Conservation in North-western Apennine (LIFE18 NAT/IT/000806), and by the SAGA and SAGA2 collaborative projects between FEM and IZSVe.

 

 

POSTER 5

Freshwater Crayfish in Serbia: Update on the Distribution

ĐURETANOVIĆ S, Stojanović K, Marković V, Zorić K, Simović P, Živić I, and Simić V

Our study aims to build upon a prior studies of crayfish distribution by consolidating findings from our fifteen years field research and summarizing existing published data. In Serbian freshwater ecosystems, we have identified the stone crayfish Austropotamobius torrentium, the noble crayfish Astacus astacus, and the narrow-clawed crayfish Pontastacus leptodactylus as native species. Unfortunately, our ecosystems have been penetrated by two invasive species: the spiny-cheek crayfish Faxonius limosus, first discovered in 2004, and the signal crayfish Pacifastacus leniusculus, more recently found in 2020. Fifteen years since the last research, we have observed that the most commonly found native crayfish is the stone crayfish, documented at 206 sites in 131 freshwater ecosystems, followed by the noble crayfish (46 sites in 31 freshwater ecosystems) and the narrow-clawed crayfish (22 sites in 11 freshwater ecosystems). Field observations have shown that changes in habitat and the increasing impact of climate change (significant droughts and floods over the past decade), primarily affect native crayfish populations. Understanding species distribution is fundamental to a wide range of biological research. Gathering additional data on species distribution is essential for enhancing our understanding of biodiversity, the functioning of aquatic ecosystems, conservation planning, climate change adaptation, and the management of invasive species. Moreover, distribution data is crucial for monitoring endangered species, such as the stone and noble crayfish, which are strictly protected under the Rulebook on the Proclamation and Protection of Strictly Protected and Protected Wild Species of Plants, Animals, and Mushrooms ("Official Gazette of RS"" no. 5/2010, 47/2011, 32/2016 and 98/2016)."

 

 

POSTER 6

The Swedish Hydrogen Gas and Crayfish Project

FAITH-ELL C, Zimmerman J and Norström S

The aim of this poster is to present a new research project called Hydrogen Gas and Crayfish (VOK). The research project was initiated by the local fisheries management NGO in Ånge municipality in Sweden. Their challenge for future generations is to be able to fish for Noble crayfish (Astacus astacus) in river Ljungan since the area has been hit by crayfish plague. At the same time, Ånge municipality is situated within the Swedish green industry belt that is currently under development. This means that P2X industries such as hydrogen gas production is developing in the region. Residue products from hydrogen gas production is oxygen and heat. To ensure the long-term survival of the crayfish and sustainable fishing of crayfish in river Ljungan for future generations, the use of water needs to be governed. Also, public, non-profit associations, municipalities and companies need to be involved in the work to promote the crayfish and prevent the spread of crayfish plague. The aim of the research project is to study how water management in hydrogen gas production can be used to ensure the survival of the crayfish. In doing so, the project can contribute to a better understanding of how new P2X industries can contribute to the sustainable use of water resources, thus improving biodiversity and creating sustainable rural development. We are doing this through a blue innovation that involves creating an ark site for Noble crayfish in connection with a hydrogen gas factory.

 

 

POSTER 11

Are Deep Karst Springs Along the Vrljika River in Croatia Long-term Protected Refuges for White-clawed Crayfish?

GOTTSTEIN S

Over the last three decades, multiple anthropogenic pressures such as pollution and hydromorphological changes, the disappearance of riparian vegetation, climate change, the presence of invasive species and crayfish plague outbreaks have radically reduced the number and density of crayfish populations in karst rivers of the Adriatic catchment in Croatia. This study aimed to determine the distribution patterns of crayfish in the Vrljika River in southern Dalmatia after the major crayfish die-off in Imotsko polje in the late 1990s. The Vrljika River with four tributaries, two karst springs and protected karst lake Prološko Blato were monitored over two years (2009 and 2010) at 20 surveyed sites using hand search and baited LiNi traps. A total of 221 specimens of two crayfish species were observed during eight nights at 6 sites. No crayfish were found in the Vrljika River. Indigenous white-clawed crayfish was detected at six sites, while introduced noble crayfish was found at two sites. The mixed populations were recorded at two sites and showed equal to twenty times lower abundance of noble crayfish introduced from Bosnia and Herzegovina. The most important refuges for the indigenous crayfish population were large deep karst springs Vrila and Vir, where the highest catch per unit effort was recorded. Over the last 15 years regular monitoring by Croatian Waters and recent local studies have not confirmed presence of crayfish in the Vrljika River. Further research requires ecological data collection with a main focus on hydromorphological state of the river and the long-term conservation of native species.

 

 

POSTER 12

Bioaccumulation Kinetics of Antihistamine Diphenhydramine in Signal Crayfish

KOUBA A, Koubová A, Sims JL, Bořík A, Brooks BW and Žlábek V

Identification of bioaccumulative chemicals in aquatic organisms has historically relied on experimental work describing the bioaccumulation of organic compounds in fish, but it has remained largely understudied in other taxa. Considering the prominent roles of freshwater crayfish in aquatic ecosystems and further attributes they possess (e.g., relatively large size, sensitivity, and easy handling), they can serve as suitable model organisms. The present study aimed to estimate ratio- and kinetic-based bioconcentration factors and derive bioaccumulation parameters of the diphenhydramine (DPH) in signal crayfish Pacifastacus leniusculus. DPH is an antihistamine with multiple modes of action, ionisable as a weak base (pKa = 8.8) and with evidence of bioaccumulation observed in various matrices globally. In a 10-day bioconcentration experiment (7 days of uptake and 3 days of elimination, pH levels 6.7 and 8.7), we analysed the concentration of DPH in crayfish hemolymph and whole body using liquid chromatography with tandem mass spectrometry, followed by calculation of kinetic-based bioaccumulation parameters. Both modelled and observed DPH effects revealed that water pH directly influenced bioaccumulation kinetics. The ratio-based bioconcentration factor was 1-2 orders of magnitude lower than in previous studies on fish. The empirically derived apparent volume of distribution for DPH was markedly higher in crayfish (416?451) than in fish (0.3?7) and humans (3?4). Bioaccumulation models driven by empirical data obtained for signal crayfish advance the science of invertebrate bioconcentration of ionisable organic contaminants, providing valuable insights for future studies in the ecotoxicology area.

 

 

POSTER 15

Morphological Variability Among Populations of Austropotamobius torrentium (Schrank, 1803) from Fentral Balkan

Marković V, Đuretanović S, Roljić R, Nlkolić V and ZORIĆ K

The Balkans is Austropotamobius torrentium (Schrank, 1803) hotspot. In its central parts (Serbia) three main stone crayfish phylogroups are present: CSE (Central and South-East European), SB (Southern Balkans) and LD (Lika and Dalmatia). In order to assess the morphological variability of the stone crayfish we analyzed ten populations from the central Balkans. A total of 145 adult crayfish (total length over 60 mm) were measured during our 2017 field study and 21 linear parameters and individual weight were taken. All measurements were standardized by postorbital length. Of analyzed crayfish 80 were males and 65 females. Performed non-parametric tests (Kruskal-Wallis) have shown that males and females differ in majority of parameters, including those related to weight. Discriminant analysis showed that abdominal and claw widths were the most important for sex separation, with the first one having larger values in females, while the second one being larger in males. Regarding populations, non-parametric tests showed that only stable parameters among male populations were a few characteristics of abdomen, claws and weight, while in female populations those were a bit more numerous. Canonical discriminate analysis was used to assess spatial morphological variability among studied populations (10 populations for males, and 8 for females). The results have shown that separation among male samples is more pronounced than in females. Alongside the first root a clear distinction of Uvac (CSE phylogroup) and Rasina (SB phylogroup) populations from the rest can be observed, while along the second root these two populations differ. Considering that analyzed populations belong to all three main phylogroups our results suggest that morphological variability of the stone crayfish is related more to specific environmental conditions (adaptations) than to separate phylogenetic lineages.

 

 

POSTER 18

Persistence of Aphanomyces astaci in White-clawed Crayfish Populations in Friuli-Venezia Giulia Region (Northeast Italy)

PAOLINI V, Basso A, Bolognini G and Pretto T

The oomycete Aphanomyces astaci is the etiological agent of crayfish plague, which is responsible for mass mortality events in European freshwater crayfish species. However, recent evidence indicates that these crayfish species exhibit tolerance towards strains belonging to the genotype A of this pathogen and records of coexistence in wild populations are increasing. An example was documented in Friuli-Venezia Giulia region (Northeast Italy) during the LIFE-RARITY project (2011-2014), when healthy populations of the endangered Austropotamobius pallipes complex tested positive for A. astaci by molecular analysis, although genotyping was unsuccessful. In 2020 and 2023, another monitoring of 5 thriving populations in the same area was performed, taking advantage of the non-invasive sampling techniques developed during the LIFE-CLAW project and the improvements in the molecular diagnostic protocols for A. astaci. Approximately 30 crayfish from each population were caught and the external cuticle was swabbed to collect putative A. astaci hyphae and zoosporangia. A total of 164 swabs were processed using a commercial kit and the DNA extracts were analysed by quantitative real-time PCR (Rusch et al. 2020). A. astaci was detected in 4 populations, 2 of which were also analysed during the LIFE-RARITY project and tested positive. The presence of A. astaci was further confirmed in one population by sequencing (Oidtmann et al., 2006). Finally, the successful application of the real-time PCR assays designed by Di Domenico (et al. 2021) supported the initial hypothesis that A. astaci genotype A was circulating in white-clawed crayfish populations in Northeast Italy.

 

 

POSTER 19

An Opportunistic Pathogen Aphanomyces laevis (Oomycota) is a Host of New Bunya-like Virus

PAVIĆ D, Bielen A, Francesconi C, Hejna O, Boštjančić LLJ and Botella L

Oomycetes are fungal-like microorganisms that cause significant disease outbreaks of freshwater animal species, including crayfish, threatening biodiversity and food safety. High-throughput sequencing (HTS) has recently facilitated the discovery of numerous oomycete viruses, whose impact may range from asymptomatic infections to reduced virulence in their hosts. However, all oomycete viruses known to date have been found in plant-associated species. In freshwater environments, Saprolegnia and Aphanomyces spp. are important oomycete pathogens of fish and crayfish belonging to the order Saprolegniales. Here, we aimed to screen for the first-time Saprolegnia and Aphanomyces isolates for viruses. We have isolated total RNA from 24 Aphanomyces spp. and 14 Saprolegnia parasitica axenic cultures, pooled the samples into two pools, and sequenced them on Illumina platform. A bioinformatics pipeline filtered low-quality reads and aligned the sequences with viral and host genomes. Next, a de novo assembly of viral reads was performed to reveal a RNA-dependent RNA polymerase (RdRp) with distant homology to the order Bunyavirales in one of the pools. Virus-specific primers were designed for reverse transcription-polymerase chain reaction (RT-PCR), confirming the virus's presence in an Aphanomyces laevis isolate from the signal crayfish in Finland. Aphanomyces laevis is usually considered a saprotrophic species associated with fish and crayfish that can in specific circumstances turn to an opportunistic pathogen. Our data are the first evidence of a viral sequence in freshwater oomycetes from the order Saprolegniales. Future studies should explore the virus's effects on its oomycete host, transmission modes, and host range.

 

 

POSTER 20

Genomic Characterisation of the White-clawed Crayfish (Austropotamobius pallipes complex) in Italy: Biodiversity Assessment and Support for Conservation Strategies

PETRETTO E, Riccioni G, Palazzo M, Morabito S, Ghia D, Fea G, Mornidelli M, Tricarico E, Carosi A, Lorensoni M, Oneto F, Capurro M, Ciuffardi L, Actis Dato G, Addabbo J, Cannobbio S, Kian D, Fracass G, Paolini V, Basso A, Pretto T, Bolognini G, Ajmone-Marsan P, the Life-CLAW Consortium and Colli L

Two species of White-clawed crayfish of the Austropotamobius pallipes complex inhabit the Italian peninsula: A. pallipes and Austropotamobius italicus/fulcisianus. Once widespread over the country, the range of Austropotamobius spp. has significantly decreased because of the introduction of diseases by non-native crayfish species and of anthropogenic pressure. A total of 1272 samples from 62 populations were collected in the north-western Italian Apennines to characterize genetic variability with both mitochondrial DNA sequencing and nuclear ddRAD (double-digest Random Amplified DNA) markers as part of the LIFE CLAW project. These analyses revealed the presence of gene pools specific to A. pallipes in the west and A. italicus/fulcisianus in the central-eastern Apennines. Within species, a lack of gene flow between different population groups was suggested by the clear correspondence between gene pool geographical distribution and water basins extension. Building on these findings, and thanks to our involvement in the National Biodiversity Future Centre (NBFC) funded by the Italian National Recovery and Resilience Plan (PNRR), we have extended the crayfish sampling area to the rest of Italy. So far, 1049 samples have been collected from 55 populations and various Italian regions including Lombardy, Friuli-Venezia Giulia, Tuscany, Umbria, and Basilicata. Moreover, consistent with the goals of the NBFC, namely the monitoring, conservation, restoration, and valorization of biodiversity in the Italian and Mediterranean landscapes, we are also targeting with the same genomic approach a number of freshwater fish species, including the Italian chub (Squalius squalus), the Italian riffle dace (Telestes muticellus) and the Italian barbel (Barbus plebejus).

 

 

POSTER 21

Developing Multiplex Assays for Crayfish Detection Using eDNA and ddPCR

RIASCOS-FLORES L, Scheers K, Brys R, Vermeylen M, Maex B, Halfmaerten D, Adriaens T and Steen F

The use of environmental DNA (eDNA) for crayfish detection has increased worldwide. The number of projects and publications significant rise with the use of techniques such as PCR, qPCR and ddPCR, as well as the increasing use of next-generation sequencing technologies like Nanopore and Illumina. The choice of technology and tools is influenced mainly by research objectives, researcher expertise and available funding. At INBO, we aim to develop an eDNA-based monitoring system for the detection of nine crayfish species in Belgium. Our approach begins with and in-silico study using sequences and primers available in the literature. Subsequently, new sequences will be generated for the target individuals to design specific-target primers and probes. These primers will be tested individually and in combination, culminating in a multiplex assay in a ddPCR for crayfish detection from environmental samples.

 

 

POSTER 22

A Contribution to the Knowledge of the Branchiobdella Species of the Balkan Region

Roljić R, Atanacković A, Nikolić V, Marković V and ZORIĆ K

Branchiobdellidans are clitellate annelids that occur mainly on astacoidean crayfishes as obligate epibionts. In Europe, all native species belong to the genus Branchiobdella Odier, 1823, which is represented by nine species. Of these, five species have been recorded in the Western Balkans Branchiobdella astaci Odier, 1823, B. parasita (Braun, 1805), B. pentadonta Whitman, 1882, B. hexadonta Grüber, 1883, B. italica Canegallo, 1928, and B. balcanica Moszynsky, 1938. The aim of the work is to improve our knowledge of the occurrence of these species in the Balkan region. Samples of Austropotamobius torrentium were collected from three streams: Miljevka, Govza and Bistrica, belonging to the River Drina basin in the municipality of Fo?a in south-eastern Bosnia and Herzegovina. Based on the morphological characteristics of the jaw - shape and dentation, the following species were identified: Branchiobdella parasita and species from the pentadonta complex. Since the two species of the pentadonta complex, B. italica and B. pentadonta, are morphologically very similar and both were previously found on A. torrentium, an exact identification of the species is possible using molecular-phylogenetic analyses that are planned in upcoming period. The obtained results are consistent with the literature data. However, if confirmed, the finding of B. italica on stone crayfish from the Black Sea basin would be of particular importance. Until now, the distribution of B. italica was restricted only to the watercourses of the Adriatic Sea basin.

 

 

POSTER 23

Morphological Variability in Introduced Spiny-cheek Crayfish Faxonius limosus (Rafinesque, 1817) Occupying Different Habitat Zones in Serbia

Roljić R, NIKOLIĆ V, Zorić K and Marković V

The non-native species Faxonius limosus belongs to the family Cambaridae and is the first invasive crayfish species to be introduced into Europe. In recent decades, it has been observed in the entire part of the Danube River in Serbia, as well as in the Sava, Tisa, Velika Morava rivers and in the ?elije Reservoir. The study included 111 specimens (48 from the Danube River and 63 from the ?elije Reservoir). The analysis includes measurement of 21 morphometric parameters per crayfish, and fitness indices were also calculated. The results partially fit within the known range of variation and represent preliminary data for both habitats. Results showed significant differences between males inhabiting different habitats, while females differed mainly in measurements of cephalothorax. Males were in better body condition compared to females, while both sexes in the Danube River had higher fitness indices compared to the ?elija Reservoir population. We can assume that the observed morphometric differences are the result of crayfish adaptation to the specific ecological conditions in the different habitats.

 

 

POSTER 25

Detection of Novel RNA Viruses in Wild Noble Crayfish (Astacus astacus) and Signal Crayfish (Pacifastacus leniusculus) in Switzerland

Zingre T, Pisano SRR, Seuberlich T and SCHMIDT-POSTHAUS H

European native crayfish populations are undergoing a strong decline due to environmental factors and the introduction of highly competitive non-native species. Pathogens are an additional threat to native crayfish. Non-native crayfish often act as carriers for devastating diseases. However, aside from Aphanomyces astaci, other infectious agents are still widely unknown. This study aimed to investigate viruses present in seven populations of wild noble crayfish (Astacus astacus) and 29 populations of signal crayfish (Pacifastacus leniusculus) in Switzerland, through high-throughput sequencing. Sequence analysis revealed the presence of 11 novel RNA viruses (one bunya-like, four hepe-like, two dicistro-like, three picorna-like, and one permutotetra-like) in the noble crayfish samples. In signal crayfish, preliminary results revealed sequences from 21 potential viruses (including novel and already described RNA viruses). The discovery of novel bunya-like viruses in noble crayfish as well as in signal crayfish without associated mortality or macroscopical alterations is of particular interest, since they are closely related to the bunya-like brown spot virus, described in 2019 from diseased native white-clawed crayfish (Austropotamobius pallipes) during a mass mortality event in France. It seems that these closely related viruses have very different impacts on their respective hosts, raising the need for further investigations on virulence factors and host susceptibility towards these viruses. This study provides a basis for future investigations, permitting to gradually fill the knowledge gap in crayfish viral diseases.

 

 

POSTER 27

More than 20 Years of Freshwater Crayfish Research in the UNESCO Site Plitvice Lakes National Park

ŠPOLJARIĆ I, Hudina S, Bielen A, Klobučar G, Pavic D, Lovrenčić L, Grandjean F and Maguire I

Freshwaters within the Plitvice Lakes National Park harbour two native European species; Austropotamobius torrentium and Astacus astacus. While A. torrentium is presumably native here, A. astacus was introduced in the past for commercial purposes, and established stable populations in the lakes and gradually displaced A. torrentium populations. Populations of A. astacus are chronically infected with Aphanomyces astaci genotype A, but are viable, while A. torrentium populations mainly inhabit streams feeding the lakes. Until now A. astaci was established in only one A. torrentium population, which resulted in drastic reduction of population size. Austropotamobius torrentium was originally recorded in five localities, while more recently, intensive research established three more populations in small streams, some of them running through basophilic pit bogs. In this presentation we will show results of more than 20 years of research that indicates the dynamics of crayfish populations conditioned by the: i) presence of A. astaci genotype A, ii) changes caused by hydrogeological processes that are part of the dynamics of the lake system, and iii) possibly by phenomena such as climate change.

 

 

POSTER 29

North Yorkshire Crayfish Forum: Collaboration for Conservation

BARLOW V, Higgins B, Renshaw S and Selway T

White-clawed crayfish (Austropotamobius pallipes) is the only native species of freshwater crayfish in the UK and has suffered a large population decline in recent years. In order to preserve its populations the North Yorkshire Crayfish Forum (NYCF) was founded in 2019. NYCF draws together organisations with an interest and passion in saving our only native crayfish. The aim of this poster is to show the importance of working at river catchment scale through partnership working, utilising the diversity in experience and specialisms of NYCF members, and the impact that it can have on practical conservation to increase effectiveness of project work, including the activities described below. In the past five years North Yorkshire Crayfish Forum has; recruited a full-time staff member, gained members from over twenty different organisations, developed a five year delivery plan, established a group of fifteen skilled volunteers, improved base-line crayfish data, set up a captive rearing facility, and created three new crayfish ark sites. The key to this has been collaboration, and resource and knowledge sharing between partners. North Yorkshire is a stronghold for white-clawed crayfish, but populations are still facing extreme pressures and uncertainty. The NYCF’s work aims to ensure the long-term survival of this endangered species. This poster will demonstrate the key to its success is continual learning and collaboration to effectively undertaking conservation across connected river catchments and across large areas like North Yorkshire.

 

 

POSTER 30

Co-evolutionary History of Japanese Crayfish and Ectosymbiotic Branchiobdellidans From a Molecular Phylogeny Perspective

KONNO T, Ohtaka A, Gelder SR and Koizumi I

The Japanese crayfish, Cambaroides japonicus, and its 11 species of obligate ectosymbiotic branchiobdellidans are endemic to Hokkaido and northern Honshu Islands in Japan. We conducted a comprehensive sampling of the host and its branchiobdellidans and sequenced each taxon for mitochondrial COI, 16S rRNA, nuclear 28S rDNA and ITS1. The results of COI were used to compare the phylogenies of the host and their ectosymbionts. Japanese crayfish show clear genetic differentiations among local populations, indicating an eastern and a western lineage on Hokkaido that are separated by the Hidaka mountains, while those on northern Honshu are part of the western lineage. In contrast, there is no significant difference in the species composition of most branchiobdellidans between the two major host lineages. A phylogenetic analysis revealed that the divergence age among branchiobdellidans estimated from the COI was earlier than the divergence time of the two lineages of Japanese crayfish. Considering the distribution patterns of branchiobdellidans and crayfish lineages, most species of branchiobdellidans would have diverged before the crayfish colonized the Japanese archipelago. However, the intra-specific phylogenetic relationship within the Cirrodrilus cirratus complex and C. sapporensis do show a clear divergence between eastern or western Hokkaido, and this is consistent with the distribution and divergence age of the host crayfish lineages. This study suggests that Japanese branchiobdellidans have maintained a high species diversity that, for the most part, occurred before the crayfish dispersion in Japan.

 

 

POSTER 32

Reproductive Biology of Pacifastacus leniusculus in a Small Tributary of Clitunno River (Tiber River Basin, Central Italy)

LORENZONI F, Carosi A, Tiberi E and Lorensoni M

Pacifastacus leniusculus (Dana, 1852) is an invasive crayfish of European Union Concern present in Italy. P. leniusculus has been recorded for the first time in the Clitunno river (Tiber River basin, Central Italy) in 2020 and, in accordance with the European regulation n° 1143/2014 a population eradication plan has been immediately drawn up as part of the LIFE IMAGINE 19 IPE/IT/000015 project. A total of 535 individuals were caught through electrofishing and trapping from November 2022 to June 2024 from Fosso Vecchio, a small tributary of the Clitunno river, and were analyzed to investigate reproductive biology. Individuals were euthanized, measured (total length, cephalothorax length and weight), sexed and analyzed. Pleopodal eggs from 35 females were counted, weighted, and measured while gonads were extracted, weighted and females’ developmental stage was attributed. The number of pleopodal eggs per females ranged from 6 to 481, a positive significant relationship between mean diameter of eggs and cephalotorax length was found. Gonadosomathic index (GSI) was calculated for both sexes. P. leniusculus females showed the highest GSI mean value in September (mean 3.7 ± SD 2.1), while males GSI mean value was higher in October (mean 0.9 ± SD 0.4). Females with pleopodal eggs were found from October to January, only one female with juveniles attached was caught in February. Our results contribute to expanding the knowledge on reproductive biology of one of the southernmost populations of P. leniusculus introduced in Italy, and results may be useful in increasing the effectiveness of control plans for this invasive species.

 

 

POSTER 33

New Record of Astacus astacus population in Brcanj stream (Bosnia-Herzegovina): Age-class Distribution and Length-weight Relationship

LORENZONI F, Carosi A, Oneto F, Capurro M, Ovčina J, Rezzoagli D and Lorensoni M

Astacus astacus (Linneaus, 1758) populations significantly globally declined in the last decades and the species has been classified as Vulnerable in the IUCN Red List. In 2022 a population of Astacus astacus was discovered in the Brcanj Stream, a chalk stream located in a karst polje in the Blidinje Nature Park (Bosnia and Herzegovina) during investigation for the NaturBosnia project. With the aim of expanding knowledge on this species a total of 226 crayfishes were sampled with electrofishing during three sampling campaigns between 2023 and 2024; individuals were sexed and cephalothorax length (CL), total length (TL) and weight (W) were measured to assess age-class distribution and determinate the length-weight relationship (LWR). Cohorts were estimated by Bhattacharya's method based on the CL frequency distribution data using the software FiSAT II. Individuals with one or both claws missing were excluded from the LWR analyses and the equation was estimated separately for both sexes. There was no significant difference in the LWR between sexes, and the relationships for the total sample showed a positive allometric growth (b>3). The population was numerous and composed predominantly of younger individuals: the scarcity of individuals composing older age classes could be due to overharvesting, observed during our fieldwork. A. astacus is native in Bosnia and Herzegovina, but this is the first record of its presence in this area, so the origin of this population should be clarified to broaden knowledge on the real distribution of the species.

 

 

POSTER 34

Optimisation of a Non-lethal Field-based Sampling Method for the Detection of Aphanomyces astaci

PISANO SSR, El Hassani N and Schmidt-Posthaus H

Aphanomyces astaci is the causative agent of crayfish plague, responsible for the decline of European crayfish. North-American crayfish, however, are resistant carriers. A. astaci DNA is detected by qPCR/PCR after extraction from the exoskeleton, sampled post-mortem (lethal destructive method - LDM). As killing of endangered species is controversial, we aimed to evaluate two non-lethal field-based sampling methods for A. astaci detection. Seventy crayfish from three asymptomatic carrier invasive species populations and one native crayfish species population undergoing a crayfish plague outbreak, were euthanized and sampled with three methods: (1) non-lethal, non-destructive method (NNM) using a dry interdental brush stored in a buffer solution, (2) non-lethal, destructive method (NDM) collecting separately one pleopod and the setae of two uropods, and (3) LDM collecting one eye, the setae of two uropods, and abdominal cuticula as a pool. DNA was extracted and qPCR for A. astaci was performed. In the symptomatic native crayfish population, A. astaci was detected in all animals with both LDM and NNM. The NDM and LDM similarly performed detecting A. astaci DNA in 2/3 of the invasive species populations. Field-based non-lethal sampling methods can be used to detect A. astaci at population level, but the minimal sampling size required for pathogen detection has to be determined. The NNM needs to be optimized in order to be used efficiently to detect carrier status. The NDM might represent an efficient/reliable field-based sampling method.

Oral Presentations from IAA24

Poster Presentations

General Assembly

Meeting Photo Gallery