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LIST OF MEETING ABSTRACTS
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Poster Presentations
POSTER 8
Fine Structure of the Spermatozoon in Three Species of (Arthropoda: Crustacea: Decapoda) Cambarus robustus, Orconectes propinquus and Orconectes rusticus: A Comparative Biometrical Study
Yazicioglu B, Hamr P, Kozák P, Kouba A and Niksirat H
The ultrastructure of spermatozoa in three species of cambarid crayfish, including Cambarus robustus, Orconectes propinquus, and Orconectes rusticus were studied and compared with eight previously studied species from different crayfish families using morphological features and biometrical data. The ultrastructure of spermatozoa show a generally conserved pattern including an acrosome and nucleus in the anterior and posterior parts of the cell, respectively, radial arms that wrap around the nucleus, and the whole cell is enclosed by an extracellular capsule. The most outstanding morphological feature in spermatozoa of three studied cambarid crayfish is the crest-like protrusions in the anterior part of the acrosome that can be used as one of the features for distinguishing the members of this family. Results of biometrical data reveal that acrosome size in the representatives of Parastacidae are the smallest, while representatives of Astacidae show the biggest acrosome. The acrosome size in species belonging to Cambaridae occupy an intermediate position between the two other families of freshwater crayfish. In conclusion, a combination of morphological features and biometrical data of spermatozoa can provide an effective tool to distinguish different species of the freshwater crayfish.
POSTER 11
Life History and Population Ecology of Signal Crayfish, the New Invader in Northern Italy
Ghia D, Fea G, Gruppuso L, Bo T, Candiotto A, Fenoglio S and Sacchi R
The occurrence of the signal crayfish Pacifastacus leniusculus in the Valla stream, north-western Italy, was one of the first reports of this invasive alien species in Italy. Since 2009 signal crayfish was spreading upstream from the artificial lake formed by a dam for hydroelectric purpose. We studied the signal crayfish population in this novel environment by trapping sessions during a year. Five sampling sites were located along the invaded range of the Valla stream, along more than 10 km. At each site, six baited traps were set once a month for two days, from April 2015 to March 2016. All signal crayfish were removed from the watercourse. Crayfish were sexed, weighted and the following morphometric parameters were measured: total length (TL), and cephalothorax length (CL). We trapped overall 433 females (mean TL: 84.7 mm) and 428 males (mean TL: 85.5 mm). Crayfish activity was correlated with water temperature. Egg-bearing females occurred from early November and hatching in late May. Sex ratio was about 1:1 in all sites except the most downstream one, where females were more abundant; and more females were caught during summer months. Crayfish TL and condition factor fluctuated during the year, but both decreased significantly moving upstream. Management actions should be promoted to limit its spreading overall within watercourses potentially suitable.
POSTER 12
Analysis of Abundance, Fecundity and Allometric Relationships from Cambarellus montezumae Females During an Annual Cycle
Latournerié-Cervera JR, García-Padilla GM, Estrada-Ortega AR and Arana-Magallón F
Cambarellus montezumae population at Xochimilco, Mexico City, is in serious problems of disappearance. This species was highly appreciated and it was regularly consumed as part of the diet of the Xochimilcas and Mexican people. Nowadays, crayfish is very scarce in this area. As a part of a collaboration research, UNAM and UAM universities have undertaken the project of assessment and rescue of native species in the area of Xochimilco. In this study, we analyze the female population of C. montezumae during an annual cycle. 42 berried females were collected in ten months of sampling (January – October). Abundance varied significantly by sampling month (p<0.05). 76.2% of females were collected during hot rainy season (April – August). Description and analysis of these females were made through: total and cephalothorax length, (TL and CTL). Large and width of abdomen, wet weight, ovigerous mass weight and number of eggs. Minimum, maximum and average values for TL, WW and number of eggs were: (28.31, 43.21, 34.5) mm, (0.58, 1.91, 0.99) g, and 13, 150 and 46.9 eggs respectively. Distributions of TL and WW were positive skewness. Allometric relationships were calculated for WW – TL (potential model, r2=0.93), CTL – TL (linear model, r2=0.86). Fecundity – TL was positive correlated (r=0.68, p<0.05). Also positive and significant correlations (p<0.05), were obtained for abdomen width and length – TL and female abundance – temperature. Ovigerous mass weight was higher on April and number of eggs per female was bigger on September. We discuss results in relation to scarcity of berried females, the decrease in the number of eggs per female, the size of first maturity, and anthropogenic impacts in the study area.
POSTER 13
Some Aspects of the Dynamic Population of a Mexican Crayfish Species, Cambarellus montezumae (Saussure) from Xochimilco
Latournerié-Cervera JR, García-Padilla GM, Estrada-Ortega AR and Arana-Magallón F
At Xochimilco's Lake, still remains a wild population of Cambarellus montezumae crayfish. This population has been declining in the last decades, because of fragmentation and loss of habitat, overexploitation, pollution, competition and predation by alien species. In this study, we analyze dynamic population of this species through indicators of abundance, meristic indexes (wet weight, WW; total length, TL; and cephalothorax length, CTL); frequency of TL distributions, cohort´s growth rate, sex ratio and allometric relationships in crayfishes of both sexes. A total of 1345 C. montezumae crayfish, were collected during a twelve-month sampling, at Xochimilco channels in 2011 annual cycle. W.W. varied between (.01 – 1.53) g, and TL (6.47 – 41.21) mm, significant differences (p<0.05) were found by sex and month. Abundance was higher during hot rainy season (April – August). Significant differences were detected in total sex ratio population (Female:Male) being almost (2:1). Allometric relationships: WW- TL and WW - CTL - were better adjusted by a potential model, and CTL – TL by a linear model. Two cohorts were identified through the annual cycle (the one at April and second in August), and growth rate was calculated for both of them using TL frequency distributions. We discuss dynamic population of this species in relation to habitat changes and anthropogenic disturbances, which have led almost to its collapse and disappearance.
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).
POSTER 21
Genetic Diversity and Differentiation of Wild Populations and Captive Stocks of the Noble Crayfish (Astacus astacus L.) in Estonia
Gross R and Kaldre K
There are about 20 crayfish farms in Estonia which produce and sell noble crayfish for restocking and enhancement of natural waterbodies and/or for human consumption. So far, the origin of captive stocks and their genetic characteristics have not been studied and likewise, there is lack of information about genetic diversity and population structure in a wild. The aim of this study was to evaluate genetic diversity and population genetic structure of captive stocks and wild populations of the noble crayfish in Estonia. A total of 1923 individuals from six crayfish farms and 38 natural lakes and rivers in Estonia were analyzed using 19 polymorphic tetranucleotide repeat microsatellite markers. For comparison, two populations from Czech Republic were included. The results showed that Estonian noble crayfish populations were on an average less variable than the Czech populations and formed two clear genetic clusters according to their geographic origin (Island of Saaremaa and mainland Estonia). The captive stocks were genetically similar to the wild populations of the same region and displayed no significant loss of genetic variability. However, two captive stocks possessed increased levels of inbreeding. The results of the study will be used for improving conservation and management plans of the noble crayfish in Estonia.
POSTER 23
Presence of Branchiobdellida in Five Population of Native Crayfish in Northern Italy: Preliminary Results
Fea G, Ghia D, Mazza L, and R Sacchi
Branchiobdellid annelids are commensal symbionts associated with crayfish populations, knowledge of their dispersion and distribution is generally scarce. The aim of this research was to identify the species of Branchiobdella isolated on the crayfish in different populations, and the prevalence among the species. We collected white-clawed crayfish Austropotamobius pallipes complex during the autumn 2013 from five creeks in Northern Italy. Worms were removed by inserting one-sidedly crayfish into a container with salty water (35 ppt): 1-minute each for claw, abdomen and cephalothorax; then branchiobdellids were placed into separate vials. The branchiobdellids identified, were Branchiobdella italica, Branchiobdella parasita, Branchiobdella astaci, Branchiobdella hexodonta and Branchiobdella pentodonta. We also found coexsistence of two or more species of Branchiobdella on crayfish at the same location. 46% of worms were present on abdomen and 40% cephalothorax while 14% were on claw. In all the populations studied at least two species of worms were detected and one crayfish was found to support four species of Branchiobdella.
POSTER 26
The River Barle Signal Crayfish Project: Assessing the Potential of Male Sterilisation as a Signal Crayfish Control Technique
Green N, Stebbing P, Bentley M, Andreou D and Lane M-R
This poster will present the methods and results to date of the River Barle Signal Crayfish Project which aims to test the effectiveness of a Sterile Male Release Technique in controlling signal crayfish on a 1.5km stretch of the River Barle Site of Special Scientific Interest, south west England, UK, between 2015 and 2017. The methodology consists of the intensive trapping and removal of all crayfish apart from dominant males (above 40mm carapace length) which are manually sterilised (vasectomised) and returned to the river. Two types of trap are used, standard funnel traps and novel artificial refuge traps which have proved far more effective and less biased than funnel traps. Detailed sampling of crayfish density, fish and invertebrates is taking place in the study area and a control site throughout and beyond the trial period. Laboratory experiments are investigating various aspects of mating behaviour including mate choice and female monoandry. The results feed into a PhD study guided by Bournemouth University, the Centre for Environment, Fisheries Aquaculture Science (CEFAS) and the Environment Agency. Trapping is being carried out by a group of 40 volunteers, many of them local people with an interest in the river. If the method is successful, the project aims to pass ownership on to local stakeholders so it can be continued over the long term without relying on external funding - a trial of this approach is also underway.
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