Abstracts
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LIST OF MEETING ABSTRACTS
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Oral Presentations
Day: 2, Session: 4, Talk: 1
Scenarios for Aphanomyces astaci Adaptations to Native and Alien Crayfish Host in Europe
Japo Jussila, Kortet R, Vainikka A, Kokko H and Makkonen J
We present here potential scenarios for A. astaci adaptation to native hosts. These are based on high, intermediate or low A. astaci virulence levels, which result in different mortality levels among the host crayfish and help understanding the main factors influencing virulence evolution. A high A. astaci virulence and the resulting high mortality level in the hosts allows high level of sporulation, i.e. transmission in A. astaci, but raises the risk of eradicating the whole host population. Intermediate A. astaci virulence and resulting on average intermediate, but strongly environment-dependent mortality level within the host population could either risk killing all hosts when mortality is intensified by a co-infection or unfavourable environmental conditions, or the parasite might sometimes have low possibilities for infecting new hosts in cases of low mortality. This could result in periods of failed reproduction or exhausting the host population, but turn out as the favoured strategy in a network of connected lakes. Low A. astaci virulence and the resulting low level mortality imposed to host population would increase the risk of cessation of infection as sporulation would likely be very low or even non-existent, as might be the case during latent infections carried by native crayfish. In the case of A. astaci infecting invasive crayfish in Europe, the adaptation scenarios are simpler and favor highly virulent A. astaci. The continuous selection for higher virulence occurring in A. astaci in alien crayfish hosts likely prevents any evolution towards lower virulence and adaptation to native European hosts as long as the alternative habitat, i.e. invasive crayfish, dominates in availability. Another potential outcome of adaptation is that the A. astaci will evolve towards two different species, one adapting to the native and one to the invasive hosts.
Poster Presentations
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 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 Qox=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 10
The Impact of Streetlights on an Aquatic Invasive Species: Artificial Light at Night Alters Signal Crayfish Behaviour
Thomas JR, James J, Newman RC, Riley WD, Griffiths SW and Cable J
Artificial light at night (ALAN) can alter the behaviour, communication and orientation of animals, and could interact with other stressors to affect biodiversity. Invasive, non-native species are one of the largest threats to freshwater biodiversity; however, the impact of ALAN on such species is unknown. This study assessed the effects of ALAN at ecologically relevant levels on the behaviour of a globally widespread invasive species, the signal crayfish (Pacifastacus leniusculus). Crayfish were exposed to periods of daylight, control (<0.1 lx) and street-lit nights to test two hypotheses: (1) signal crayfish under natural conditions are nocturnal animals and (2) ALAN reduces the duration of crayfish activity and intraspecific interactions, whilst increasing their propensity to use shelter. Our results confirm that signal crayfish are largely nocturnal, showing peak activity and interaction levels during control nights, whilst taking refuge during daylight hours. However, when exposed to ecologically relevant simulated light pollution from a streetlight at night, activity and interactions with conspecifics were significantly reduced, whilst time spent sheltering increased. Global anthropogenic changes such as ALAN may alter the life history traits and behaviour of invasive species and ultimately influence their impact on invaded ecosystems. The results of the present study suggest that ALAN could reduce the success of signal crayfish in urban areas, by drastically reducing their nocturnal activity. This study is the first to show an impact of ALAN on the behaviour of an invasive, non-native species, and provides information for the management of invasive crayfish in areas where ALAN is prevalent.
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 17
North American Branchiobdellida (Annelida: Clitellata) or Crayfish Worms in France: The Greatest Diversity of These Alien Ectosymbionts in Europe
Parpet JF and Gelder SR
Over the last five years, biomonitoring of freshwater bodies resulted in alien crayfishes being collected from the Garonne, Loire, Seine and Rhône basins in France. These crayfishes (Pacifastacus leniusculus (Dana, 1852), Procambarus clarkii (Girard, 1952), Orconectes limosus (Rafinesque, 1817)) from North America also carried ectosymbionts of the order Branchiobdellida (Annelida, Clitellata) or crayfish worms. Initially we reported (Gelder et al., 2012) the distribution in France of Xironogiton victoriensis Gelder and Hall, 1990, Cambarincola gracilis Robinson, 1954 and Cambarincola okadai Yamaguchi, 1933 on the signal crayfish, P. leniusculus, indigenous to the Pacific Northwest of North America; additional information is included here. Signal crayfish found in the Seine basin also carried Triannulata magna Goodnight, 1940, and this is the first record of this species in Europe. Louisiana red swamp crayfish, Pr. clarkii, were collected in the Adour basin along with their endemic, Cambarincola mesochoreus Hoffman, 1963. This is the first report of both host and branchiobdellidan in France. A unique host/branchiobdellidan combination was discovered when western North American X. victoriensis was observed on eastern North American spiny cheek crayfish, Orconectes limosus (Rafinesque, 1817). Although France has the most reported alien branchiobdellidan species in Europe, a number of other countries also have established North American branchiobdellidan populations. The impact of these alien species on the endemic Branchiobdella spp. is unknown, but warrants concern and further study, besides investigating their impact on other invertebrates in the freshwater ecosystem.
POSTER 28
Management of the Native White-clawed Crayfish, Austropotamobius pallipes, in the Province of Girona
Montserrat J, Macias M and Torres F
The native white-clawed crayfish (Austropotamobius pallipes) was a species commonly found in most watercourses in the basins of the rivers Fluvià, Ter and Muga until the end of the 1970s, when the crayfish plague Aphanomyces astaci arrived, a water mould that led to the disappearance of almost all the populations in these river basins. The white-clawed crayfish populations are currently found in second-order or larger seasonal rivers and fast-flowing streams where, due to some kind of natural barrier (drought in the lower reaches of the watercourse, cliffs, etc.), the fungus was unable to grow. Moreover, during the 1990s, the red swamp crayfish (Procambarus clarkii) population expanded rapidly in the basin and the situation became far worse, since the North American species is both a carrier of the crayfish plague and resistant to this fungal disease. Later, the signal crayfish (Pacifastacus leniusculus) arrived in the Ter River and the spinycheek crayfish (Orconectes limosus) arrived in the Muga River Basin, both species being carriers of the pathogen Aphanomyces astaci. This situation means relict populations of the white-clawed crayfish cannot expand and are forced to survive in the most inaccessible seasonal rivers and fast-flowing streams, facing the danger of a new outbreak of crayfish plague.
Oral Presentations from IAA21
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General Assembly
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