Abstracts
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LIST OF MEETING ABSTRACTS
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Oral Presentations
Day: 3, Session: 2, Talk: 1
The Annotation of two Aphanomyces mitochondrial Genomes from A. astaci and A. invadans
Makkonen J, Vesterbacka A, Martin F, Jussila J, Diéguez-Uribeondo J, Kortet R and Kokko H
The genus Aphanomyces (Saprolegniales, Oomycetes) includes species in both aquatic and terrestrial environments. Two important pathogens and aquatic species are Aphanomyces astaci, the cause of crayfish plague and its close relative and Aphanomyces invadans, which causes the epizootic ulcerative syndrome on fish. In this study, we have assembled and annotated the first mitochondrial genomes of Aphanomyces from the whole genome shotgun sequence reads (PRJNA187372; PRJNA258292, respectively). The assemblies were generated from A. astaci Pc-genotype strain APO3 and A. invadans strain NJM9701. The sizes of these mtDNAs were 49,489 bp and 49,061 bp for A. astaci and A. invadans, respectively. The species shared similar genetic content and organization encoding 36 proteins, two ribosomal RNAs, three putative open reading frames and 33 transfer RNA’s of 19 amino acids for peptide synthesis. Both species also had a large inverted repeat region (LIR) of approximately 12 kb, the LIR contained large and small ribosomal subunits and eight protein coding genes. These annotated mitochondrial genomes serve as a valuable genetic backbone for further development of diagnostic methods, genotyping and phylogenetic and migration studies of the parasitic species of Aphanomyces.
Day: 3, Session: 3, Talk: 2
Survival, Recovery and Cardiac Activity of Three Crayfish Invaders Under Sub-zero Temperature
Yazicioglu B, Kuklina Iryna, Buřič M, Císař P and Kozák P
The effect of acute exposure to subzero temperature on the heart rate and recovering capacity of three invasive crayfish species (Orconectes limosus, Pacifastacus leniusculus, Procambarus clarkii) was investigated. These species are successful invaders in European freshwater ecosystems, in many respects due to adaptability to the wide range of environmental conditions including tolerance to temperature changes. The experiments were designed to evaluate cardiac activity (based on using of non-invasive sensor), survival and recovery of crayfish after short-term (30 min) and prolonged (60 min) exposure to sub-zero temperature (-18 ºC). All O. limosus and P. leniusculus died within following 12 hours after both short and longer exposure. In contrast to them, all P. clarkii successfully survived freezing, thawing and subsequently recovered after short-term exposure, while a quarter of the P. clarkii specimens successfully recovered even after prolonged exposure. In all tested species heartbeat was measurable several hours post exposure, although cardiac activity gradually declined in O. limosus and P. leniusculus after reaching the point of no return. The heart rate of P. clarkii decreased the most abruptly and the recovery to nearly pre-exposed state took longer time (˜ 35 min) than for O. limosus (˜ 25 min) and P. leniusculus (˜ 28 min). During freezing-thawing cycle both species demonstrated smoother heartbeat decline and faster heartbeat recovery to a non-return point, that can explain the mortality observed in O. limosus and P. leniusculus. Faster responsiveness to acute conditions and more gradual subsequent recovery of P. clarkii, as reflected in the heart rate course, seems to be more successful strategy for survival. Our findings can shift the knowledge in terms of understanding of wider ecological distribution of P. clarkii as well as insight into mechanisms of invasive crayfish adaptability.
Day: 4, Session: 3, Talk: 4
Could Crayfish Care About Safety of Beer? - A Long Way from the Research to the Practical Use
Pavel Kozák, Kuklina I, Kouba A, Voldřich M, Dědič R, Janoušek J, Aliaksandr P and Císař P
Over the past decades, ecological status of the freshwater crayfish has been drastically changing from the sensitive indicator of aquatic environment to the tolerant species which can survive the wide range of unfavourable conditions, but despite all conventions on being or not being the proper bioindicators, crayfish are still regarded as essential aquatic community playing various key roles in the freshwater ecosystem. We developed a system for monitoring of etho-physiological status of crayfish combining analysis of the heart rate and detection of movement as basic parameters. Monitoring of cardiac activity is done with the aid of a non-invasive sensor and locomotion of crayfish is recorded by cameras enabling analysis of the complex data by a software developed particularly for this purpose. A range of stimuli where crayfish showed response to both adverse and common environments were successfully tested. We examined crayfish reactions to such chemicals as chloramine, chlorides, nitrites, as well as to the various natural stimuli (odours of food, conspecifics, predators and others). This monitoring technique is easy due to absence of long and complicated analyses, since measured parameters, locomotor and cardiac activity, are evaluated in a real time. The sophistication of such biomonitoring is consisted in reliable combination of behaviour and physiology that affords an opportunity of detection of individual animals reaction to environmental changes. After registration of the whole system as national patent, the first yield of its practical application was an agreement with the local South Bohemian brewery where the biomonitoring system is expected to guard the water used for production of beer.
Day: 5, Session: 2, Talk: 1
The Use of a Traditional Māori Harvesting Method, the Tau Kōura, for Monitoring of Freshwater Crayfish (kōura, Paranephrops planifrons) Populations in the Te Arawa Lakes, New Zealand
Ian A. Kusabs
Freshwater crayfish (Paranephrops planifrons) are endemic to New Zealand where they are known locally by the Māori name ‘kōoura’. Kōura are an important component of lake food webs and support important customary fisheries for Māori in the Te Arawa lakes of New Zealand. Anecdotal evidence suggests that kōura populations have declined markedly since European settlement in the late 19th Century. Environmental factors implicated in this decline include, introductions of exotic fish and plants and eutrophication. Until recently, there was a lack of quantitative information on kōura abundance and ecology that made it difficult for tribal and government agencies to manage kōura populations in the lakes. However, development and use of the tau kōura, a traditional Māori harvesting method, has led to a resurgence of research and monitoring on lake-kōura populations. This method involves the placement of bracken fern bundles on the lake bed for kōura to take refuge in. It has advantages as a monitoring tool over conventional methods, as it samples all kōura size classes, can be used in turbid waters and at a wide range of depths, and does not require expensive equipment or specialised expertise. The tau kōura is now the principal method used to collect data on kōura populations in the Te Arawa and Taupō lakes. It has been used to determine environmental factors influencing kōura abundance and distribution, in the development of sustainable fisheries regulations, and in resource management decision-making.
Day: 5, Session: 3, Talk: 2
People's Perception of Crayfish
Bram Koese
Different audiences in The Netherlands were invited to ‘draw a crayfish’ at the beginning of a lecture. On average, people mentally reproduce crayfish with 7.04 legs (range: 0-14) and 1.67 clawed legs (range: 0-8). However, there seems to be consistent variation in perception between different groups of people (e.g., children, men and women). Various concepts of a crayfish will be discussed. Other than aqcuiring drawings and data, asking people to draw crayfish can significantly increase the interest in your lecture.
Poster Presentations
POSTER 4
PIT Tagging Effect on Noble Crayfish (Astacus astacus L.) Survival
Kaldre K and T Paaver
A laboratory experiment was conducted to assess the potential impacts of 1.5 X 7 mm passive integrated transponder (PIT) tags on survival of noble crayfish (Astacus astacus L.). 30 noble crayfish (mean TL 96.9 ± 4.4 mm, 26 females and 4 males) were internally implanted with PIT tags and were kept together with untagged (as control) 30 crayfish (mean TL 96.0 ± 5.4 mm, 23 females and 7 males) in three 1 m3 tanks (10 tagged and 10 untagged crayfish in each) and maintained for 219 days at room temperature with a light regime of 16 h: 8h LD. 31 noble crayfish originated from a natural lake and 29 noble crayfish originated from a crayfish farm. 90% of tagged crayfish and 77% of untagged crayfish died during the experiment. The highest survival rate (30%) was observed in the third tank where the mean TL (93.4 ± 4.9 mm) was smaller than in the first (97.6 ± 3.0 mm) and in the second tank (98.5 ± 5.0 mm) where the survival rates were 10%. All survived crayfish originated from the crayfish farm. We can assume that smaller crayfish tolerate tagging better and the farmed crayfish survive better than wild ones.
POSTER 5
Mate Choice in Spiny-cheek Crayfish (Orconectes limosus, Rafinesque 1817): Females Prefer Males from the Same Population, Males not
Kubec J, Kouba A, Kozák P and Buřič M
Investigating of different effects on mate choice belong to major principles in behavioural and ecological studies. The mate choice is often based on recognition of conspecifics and social experiences (e.g. hierarchy, aggression or fighting), which play important roles in decision-making. In crayfish, it is known that females, which have large energy cost, are more choosy than males. We analysed mate selection of the spiny-cheek crayfish (Orconectes limosus) in the laboratory conditions. Our objective was to explore the effect of different origin of individuals (three geographically separated populations) on preference in mate choice. Both sexes were divided into triad groups (male with a familiar and unfamiliar female; female with a familiar and unfamiliar male). Our results suggest that spiny-cheek crayfish females choose mates from the familiar population, whereas males do not exhibit any specific preference between conspecifics from all. Our study offers information around reproductive behaviour that previous experience enables invertebrate females to easier decision making. While the males confirmed hypothesis about lesser selectivity. This study has the potential for future research on the largely overlooked field of mate choice in invertebrates.
POSTER 16
Assembly and Annotation of the Marbled Crayfish Genome
Gutekunst J, Falckenhayn C, Gatzmann F, Raddatz G and Lyko F
Marbled crayfish (Procambarus virginalis) are the only freshwater crayfish known to reproduce by cloning (apomictic parthenogenesis). Notably, among genetically identical offspring raised in the same environment distinct phenotypic differences can be observed. These characteristics render the marbled crayfish an interesting laboratory model. A prerequisite for introducing this triploid arthropod as a new model organism and focus of this thesis is the identification of its complete genome sequence. We experimentally determined the genome size at approximately 3.5 Gbp by k-mer analysis and flow cytometry. High coverage sequencing data (~70X) of one individual female was used for a first de novo draft assembly with a length weighted median scaffold size (N50) of 40 kb. Assessing genome completeness using the benchmarking software BUSCO we were able to identify 56% complete and 21% fragmented (out of 2675) conserved single-copy arthropod orthologs. Single nucleotide variations (SNP) analyses of four additionally sequenced individuals from different strains confirmed clonal reproduction and enabled us to describe genomic characteristics such as triploidity and common genotypes. By interspecies comparisons to the closest relative, the sexually reproducing Procambarus fallax, and preliminary automatic genome annotation of about 15,000 protein coding transcripts we found potential alterations in meiosis related genes. These findings provide new insights into mechanisms of parthenogenesis. Genomic data and manual curation services are, after registration, publicly accessible at our Marmorkrebs webserver (http://marmorkrebs.dkfz.de).
Oral Presentations from IAA21
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General Assembly
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