Abstracts

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LIST OF MEETING ABSTRACTS

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Oral | Posters

Oral Presentations

 

 

Day: 2, Session: 3, Talk: 3

Pitfalls in the Application of Molecular Methods for the Diagnosis of Crayfish Plague

Satu Viljamaa-Dirks, Heinikainen S, Riva R and Pelkonen S

Crayfish plague, a highly contagious disease of the European crayfish species, is caused by the oomycete Aphanomyces astaci. Aphanomyces astaci is a parasite of the North-American crayfish species. It resides in the cuticle of its host and spreads by zoospores. In the case of acute illness of the European crayfish, the production of zoospores is massive and the crayfish in the vicinity are effectively infected. However, the virulence of the A. astaci strains is variable and even a latent infection in the highly susceptible European host is possible. Before the development of molecular methods the diagnosis of crayfish plague relied on the cultivation of the causative oomycete, a complicated and often unsuccessful process. Specific PCR based methods improved the diagnostic results considerably even enabling the quantitation of the pathogen load and the further characterization of the strain. At the same time they present new challenges in interpreting the results. Standardized protocols especially concerning sampling schemes are lacking, as well as external quality controls. In addition, freshwater environment and the crayfish within can contain numerous unknown organisms that may interfere with the detection and characterization of A. astaci. A few examples are given concerning the problems arising from the insufficient validation of the molecular methods.

 

 

Day: 3, Session: 3, Talk: 5

Crayfish Role in a Canyon-shaped Reservoir: Case Study from the Nýrsko, Czech Republic

Veselý L, Bláha M, Buřič M, Fořt M, Pešek V, Kozák P, Ruokonen TJ, Ercoli F and Kouba A

Trophic webs in almost every ecosystem contain many units, which are linked together and in aquatic systems crayfish are one of the most important. They are considered keystone species as well as ecosystem engineers there and may represent up to 85 % of benthos biomass. Their omnivorous diet complicated evaluation of their position in the food chain. Using carbon and nitrogen stable isotopes we investigate the trophic role of noble crayfish (Astacus astacus) in canyon-shaped reservoir. We sampled all units of food chain (fish, zoobenthos, zooplankton, primary producers, and detritus) using wide range of methods such as manual collection, angling, trapping, and scuba diving. Our results revealed that role of crayfish changes during ontogeny. Also crayfish diet varied between season (spring, summer, autumn) and habitats (rubble slopes/ beaches). Additionally, we found that crayfish are an important component in nutrient cycles due to their ability to connect different depth zones of reservoir.

 

 

Day: 4, Session: 1, Talk: 1

KEY NOTE: Crayfish and Companions Across the Tree of Life

Pablo Vargas

Crayfishes are not actually crustaceans. Well, the term Crustacea should not be used because crustaceans do not form a single evolutionary (monophyletic) group without insects. However, a more inclusive group of Hexapoda (mostly insects) + former Crustacea named Pancrustacea is currently recognised in the Tree of Life. In this presentation we will go across the natural classification of living organisms to find out where crayfishes and travel companions (pathogenic moulds, Rhizaria diseases, invasive angiosperms, toxic cyanobacteria blooms, humans) are placed in the Tree of Life.

 

 

Day: 5, Session: 4, Talk: 2

Environmental Education and Awareness, Fundamental Tool in the Conservation of the Native Crayfish

Núria Valls, Llamas S and Comas O

The Association of Defence and Study of Native Fauna & Flora (ADEFFA) runs a conservation program of the native crayfish in the Llobregat river basin since 2005, including the study of populations, captive breeding, repopulation, removing invasive species, land custody contracts, habitat preservation and environmental education. All activities within the conservation program run from the Generalitat de Catalunya. ADEFFA believes that environmental education is an essential tool in the conservation of the native crayfish, especially in the fight against the spread of invasive crayfish species. The main objective of ADEFFA’s environmental education program is to present the risk factors that threat native crayfish populations and how people can contribute to their conservation. The activities are focused to general public, schools, and specific groups such as fishermen, hikers, etc. A highlight of the activities that has been under development for 5 years is the “Day of the invading crab catch at Merlès River. Has a main purpose, which is the environmental awareness of the participants related to the introduction of invasive crayfish species. Explaining how this species affect native crayfish, how invasive species deteriorate river ecosystems and the need for public to collaborate not expanding invasive species are the main goals of the date. Two or three dates are held annually. The activity takes place overnight and it is aimed at all ages. The result is a great success of participation, more tan 200 persons per event, a high disclosure in nearby villages and around 25000 crabs caught (mainly American signal crayfish) since 2010. A pioneering experience that is worth to be known.

 

Poster Presentations

 

 

POSTER 2

Crayfish Epibionts Branchiobdella sp. on the Stone Crayfish in the Czech Republic

Vlach P and ŠrámkováL

This contribution evaluates the occurrence of crayfish epibionts Branchiobdella inhabiting stone crayfish in the Czech Republic. The study was conducted in 8 localities (from app. 40 known localities), respecting its natural range in the country. In total, we determined 723 individuals of 4 species: Brynchiobdella pentodonta,/i>, B. hexodonta, B. parasita and B. astaci. B. pentodonta dominated (403 ind.) in the whole sample, and also B. parasite,/i> occurred frequently (316 ind.). On the other hand, B. hexodonta was recorded only three times and B. astaci only once in the left tributary of Novosedlský brook in Upper Palatine Forest. The most variable locality was Huníkovský brook with 3 recorded Branchiobdella species - B. parasita, B. pentodonta and B. hexodonta, whose occurrence was recorded only in this stream. B. parasita was mostly the dominant species, or occurred equally to B. pentodonta in the stream Chýlava. On the contrary, in Zubrina, the abundance of B. pentodonta prevailed. The highest abundance of Branchiobdella sp. was recorded in Zubrina (17 ind. per one crayfish on average), conversely the lowest number in Medvedí brook was observed (0.3 ind. per crayfish). Moreover, we found out that B. pentodonta significantly preferred its position on crayfish chelae, whereas B. parasita inhabited the whole crayfish body equally, except for chelae. The last findings could correspond with interspecific competition between both species.

 

 

POSTER 9

Metabolic Rate of Cambarellus montezumae (Crustacea: Cambaridae): Effects of Size and Seasonal Changes

Latournerié-Cervera JR, García-Padilla GM, and Estrada-Ortega AR

The measurement of metabolic rate is a key element of a species energy balance. The evaluation of respiratory metabolism in natural conditions, allows us to know the energy requirement of the animal for different processes including growth, activity, reproduction, among others. The objective of this study was to know the element (R) of the energy budget equation: C = P+R+F+U (IBP, 1968) in Cambarellus montezumae, during hot rainy season (May – August) and transitional months (September – October) in the area of study. Recently collected samples of crayfish (n=15) representing small, medium and large sizes of both sexes were employed in respirometry experiments, using a closed respirometer. The temperature and water quality were similar to the conditions of the sampling site. Two measurement periods were used: (noon and evening). Average routine metabolic rate was used for comparisons (QO₂: mg O₂/g. dry weight/h) and was converted to cal/g.dw/day using the Q_ox=3.31 cal/mgO₂ (Brafield & Solomon, 1972). Comparisons for size and month were made by ANOVA factorial (3 X 6) and Tukey test post hoc (p<0.05). Significant differences were obtained by month and size. QO₂ was similar between the months of the rainy season, with a temperature average range of (22.3 ± 1.6°C) and had a significant decrease (p<0.05) in October. Relationships of QO₂ – WW were calculated for all months using a potential model. We discuss results in relation to energy requirements of the species for growth and reproduction and its potential use for intensive management.

 

 

POSTER 14

Detection of Invasive Crayfish Populations by Environmental DNA in Fishponds from the Natural Park of Brenne

Mauvisseau Q, Coignet A, Delaunay C, Pinet F, Bouchon D and Souty-Grosset C

Environmental DNA (eDNA) is a powerful method for assessing the presence and the distribution of invasive aquatic species. We used this tool in order to detect and monitor several invasive crayfishes Procambarus clarkii, Orconectes limosus and Pacifastacus leniusculus,/i> present or likely to invade the fishponds of the Natural Regional Park of Brenne, one of the most important wetland in France and listed as an International RAMSAR wetland zone since 1991 We designed specific primers for each crayfish species, and set up an experimental aquarium approach to confirm the specificity of the primers and the sampling protocol. We analysed samples taken in the Natural Regional Park of Brenne in 2014 and 2015. The field experiment has proven the reliability of the eDNA detection method. Both experiments confirm that qPCR using SybrGreen protocol with the same primers give better reliable results that with TaqMan protocol. After optimization of the eDNA detection in water samples, it is concluded that sampling must be made during the main period of activity of crayfish, i.e. in summer. This method is a powerful tool for establishing the presence or absence of invasive species in the numerous ponds (more than 2000) in the National Regional Park of Brenne.

 

 

POSTER 15

Reproductive Cycle of the Marble Crayfish from an Established Population in Croatia

Cvitanić M, Hudina S and Maguire I

The marble crayfish (Procambarus fallax f. virginalis) is a relatively new non-indigenous crayfish species that has established populations in Europe. Until today, it is the only known decapod species with parthenogenetic reproduction. Established population of marble crayfish was recently discovered in a gravel pit in Northwest Croatia. Apart from parthenogenetic reproduction, the invasion success of this species stems from its early maturation, and higher fecundity compared to other crayfish species. Therefore, the aim of this study was to examine the year cycle of the marble crayfish in Croatia, and its potential (number of ovarian eggs) and realized fecundity (number of pleopodal eggs and juveniles). Our results show that all 140 examined individuals were reproductively active during the whole sampling period. Peaks of reproduction activity were recorded from September to November, when both individuals with pleopodal eggs or juveniles as well as individuals with ripe ovarian eggs were recorded. The smallest reproductively active female was 40.81 mm TL, while reproductive output increased with size (TL). The average number of ovarian eggs was 297. The average number of pleopodal eggs was 15% lower than the number of ovarian eggs, while number of juveniles attached to pleopods was reduced by 50% from ovarian egg count. This represents a lower brood loss compared to other crayfish species. Due to almost constant reproduction, early maturation and relatively high potential and realized fecundity in an established population in Croatia, the marble crayfish represents a major threat to the surrounding waterbodies and their native crayfish fauna.