Abstracts

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LIST OF MEETING ABSTRACTS

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Oral | Posters

Oral Presentations

 

 

Day: 2, Session: 2, Talk: 1

STURE ABRAHAMSSIB MEMORIAL LECTURE: Melanization: An Evolutionary Conserved Innate Immune System

Kenneth Söderhäll

Although invertebrates lack the complexity of the adaptive immune system and rely solely on innate immunity their amazing diversity, abundance and evolutionary success argue for a highly efficient defense system against infections. Innate immune responses include phagocytosis, synthesis of antimicrobial peptides (AMPs) and activation of proteolytic cascades that lead to melanization (the prophenoloxidase activating system,ProPO-¬-system) and blood coagulation. The ProPO system is a proteolytic enzyme cascade, which is activated by minuscule amounts (picogram per l) of cell wall products from microorganisms (LPS, PGN and glucans) and subsequently generates immune factors such as for example peroxinectin. The proPO-¬-cascade requires careful regulation by a spatial and temporal control to avoid dangerous side effects. All of the steps in the proPO-¬-cascade are shared with the proteinase cascade leading to the activation of the Toll pathway for production of antimicrobial peptides. Recently we showed that caspase 1 is involved in release and regulation of proPO and that fragments from proPO are antibacterial and further that white spot syndrome virus inhibits the proPO-system and avoids the immune system and can replicate. I will in my talk give a history of our work on melanization.

 

 

Day: 2, Session: 3, Talk: 5

Host-pathogen Network Analysis of Saprolegniales: Host Preference and Specificity of Aphanomyces astaci

Jose V. Sandoval Sierra and Diéguez-Uribeondo J

Ecological network analyses are allowing a better understanding of the biodiversity complexity. This type of analyses provides a systematic way of representing, characterizing, and comparing the complexity of the ecological communities and their interactions, where the species are represented by nodes and the interactions by links between nodes. The Saprolegniales (Oomycetes) comprise the crayfish plague pathogen Aphanomyces astaci, and their species have complex network interactions with their of hosts. In this study, we have applied ecological network analyses to a total of 1362 isolates corresponding to 51 species of Saprolegniales isolated from 107 species of different hosts, e.g., crustaceans, insects, amphibians, turtles, fish (both from embryonic and adult stages) as well as plants. The results showed that specialization indexes of Saprolegniales species (d) ranged from 0.51 to 1.00. The Shannon diversity (t = 58.502, df = 1962.4, p < 0), and niche overlap values (t = 192.05, df = 1421.5, p < 0), and the index for complementary specialization (H2’) (t = -190.55, df = 1847.60, p < 0) appear to indicate that some species posse high host specialization, e.g., A. astaci, which have a higher specialization index of 0.95 for freshwater crayfish species. The results also show that, in Saprolegniales, the preference and specificity for host species have been often overlooked due to the fact that the majority of the species also have a saprotrophic lifestyle.

 

 

Day: 3, Session: 1, Talk: 1

KEY NOTE: Parametric Models to Trace the Spatiotemporal Evolution of Populations and Lineages

Isabel Sanmartín

Parsimony approaches were for many years the only option available for inferring the biogeographic history of populations, species, and lineages. The development in recent years of parametric approaches based on probabilistic models of range evolution has revolutionized the discipline, widening the range of questions that can be addressed with genetic and spatial data. These models, typically based on continuous-time discrete state Markov chain processes, are inspired by models used in phylogenetic studies to trace the evolution of a character in a phylogeny, but here the character states are the geographical ranges of the species. Unlike parsimony approaches, they allow integrating time and other sources of evidence (species’ ecology, Earth history) and account for the uncertainty in phylogenetic and ancestral state reconstruction. Here, I review these approaches, their rapid growth, and current challenges. Some models, such as maximum-likelihood DEC and derivatives, provide detailed reconstructions of the history of individual lineages, including numerous types of biogeographic processes (extinction, range expansion, dispersal, speciation), at the expense of computational efficiency. Other class of models use Bayesian inference to jointly estimate phylogenetic relationships, divergence times, and ancestral ranges given molecular data and the geographic location of sequences. Because of their simple underlying biogeographic model, and the use of Bayesian MCMC to ease computational tractability, these models have become very popular in phylogeography to answer a wide range of questions, from routes of viral spread to historical patterns of gene flow across populations. In my talk, I will focus on the use of these models to test hypotheses in macroevolution and ecology using datasets of multiple lineages inhabiting the same region and a hierarchical Bayesian approach to account for species-specific differences. Finally, I will describe recent advances, including the development of time-heterogeneous models to incorporate the temporal dynamics of the dispersal process, partitioning the contribution of abiotic factors to migration rates, or the use of non-stationary models to model mass extinction events.

 

 

Day: 3, Session: 2, Talk: 3

Comparing Classic Crayfish Cage Surveillance with eDNA Water Monitoring During an Ongoing Crayfish Plague Outbreak in Norway

David Strand, Johnsen SI, Rusch J, Knudsen SW, Agersnap S, Larsen W, Rask-Møller P and Vrålstad T

The use of environmental DNA (eDNA) for detection and quantification of aquatic organisms is a rapidly growing field with a great potential for streamlined inventory- and monitoring purposes. The TARGET-project aims at implementing eDNA approaches for monitoring the red-listed Astacus astacus and its threats. In 2014-2016, we followed an outbreak of crayfish plague in the Norwegian Halden watercourse which had resulted from illegal transfer of Pacifastacus leniusculus. A surveillance program based on cages containing noble crayfish was already established, thus the spread of disease was monitored by observing and diagnosing mortalities in the cages, and water samples were collected regularly. Water (~5 L) was filtered on-site through glass fiber filters, and each sample was analysed using species specific qPCR assays for the crayfish plague pathogen Aphanomyces astaci, and the crayfish A. astacus and P. leniusculus. eDNA from all three species was successfully detected in the water samples. Crayfish plague spores was detectable in the water before the caged crayfish succumbed to the disease. The infection source (signal crayfish), representing a scarce P. leniusculus population (0.11 CPUE) in the southern part of the lake, was detected at trace levels. Furthermore, eDNA from noble crayfish was readily detected and increased in quantity during the mortalities, before decreasing to trace levels about 4-8 weeks after the outbreak. Our study demonstrates an efficient and non-invasive approach for combined eDNA monitoring of native crayfish and its threats (invasive crayfish and crayfish plague) from the same water samples.

 

Poster Presentations

 

 

POSTER 1

Adaptive Response to Early Dominance of an Acute Invader? A Case Study of Native Crayfish

Lele S-F and Pârvulescu L

Successful invasive species compete for the same existing resources with related native species, frequently driving the latter to the cusp of extinction because of a lack of adaptive response. In this paper we analysed the behavioural relationships between two species of crayfish, the native Astacus leptodactylus and the invasive Orconectes limosus in an ongoing invasion process in the Lower Danube. We tested the species’ ability to acquire food and shelter in laboratory experiments in both intra and interspecific confrontations. Moreover, we extended the investigation in the field by collecting biometrical data from crayfish individuals in old, new and non-invaded Danube sectors in order to compare the crayfish body fitness. The innate aggressive behaviour of the invasive crayfish reveals a pattern directed even towards its congeners, while the native species displays a more tolerant conspecific behaviour. With respect to interspecific confrontation, the invasive crayfish males and females exhibited prone sex-specific dominance behaviour regarding shelters. A roughly balanced behaviour was noticed for intersexual confrontations, larger specimens being slightly more dominant. The results of this study also highlight that the occupancy of a shelter is more disputed than food resources, which appear to be opportunistically achieved. Field data revealed better body fitness indexes in non-invaded sites but also in growing populations in old invaded Danube sector. Considering those results, we hypothesise that the stress caused by dominance might lead to acute decrease of the invaded native populations biological quality and thus increasing the incidence of the crayfish plague which consequently resulted in the declines. Further investigations may reveal if there is any hope for recovery of the native species.

 

 

POSTER 7

The stone crayfish in the czech republic: lost-and-found in last seven years

Vlach P, Fischer D and Svobodová J

Within the period 2012-2015, an intensive research concerning: 1. mapping the occurrence of stone crayfish; 2. monitoring of presently known populations; 3. an evaluation of ecological demands of this species, was carried out. This contribution focuses on newly described localities, losses of some populations, and populations affected by a dramatic decrease in population densities in some localities. Moreover, the contribution introduces a hypothesis or/and particular reasons for that decrease or extinction. The extinction in Úpor brook and Hýskovský brook has already been published; recently we have recorded the following losses: Zákolanský brook, Bertínský brook, Vlcí brook, Kornatický brook, Hrádecký brook, and Medvedí brook. Whereas the combination of crayfish plague and (probably) low water quality caused the total mortality in lower part of the Zákolanský brook, crayfish plague outbreak killed crayfish in Kornatický and Hrádecký brook in 2015. Conversely, there was a lethal concentration of BOD5 in Vlcí brook. Also dramatic droughts in 2015 influenced the population densities in Chocenický and Prešínský brook. The mass mortality in Klabava was caused by a combination of stream acidification and toxic metal accumulation. The reasons for other losses are mostly speculative. On the other hand, within the mapping campaign, we found more than 10 new populations of stone crayfish. Nevertheless, the newly recorded occurrences correspond with a present range of this species in the Czech Republic.

 

 

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 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 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 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 24

Effect of Pharmaceuticals on Crayfish

Shaliutina O and Bláha M

The release of human pharmaceuticals and personal care products into aquatic ecosystems continues to be a serious environmental problem. There is a staggering list of pharmaceuticals that have been detected in surface water, groundwater and tap water. These compounds typically modify the physiology or behavior, of the intended target system, without lethal effect. The wide range of entry points into freshwater systems reaffirms that animals living within those habitats face continuous exposure to pharmaceuticals, even if only at low doses. Crayfish are a crucial invertebrate in freshwater ecosystems. They are omnivorous, and occupy a key position in the trophic web as both predator and prey. With the importance of crayfish to their ecosystems, the introduction of pollutants such as pharmaceuticals, could have negative effects to crayfish populations. For example, pharmaceuticals can cause a mediating aggressive behavior. It has been demonstrated that crayfish injected with serotonin (antidepressant) fights lasted considerably longer. Also, the lasting impact of pharmaceuticals leads to immune system function decline, which greatly increases the mortality rate. Moreover, they can slow down synthesize and release of hormones from the X-organ sinus complex, and thus influence molting, gonad development, water balance, blood glucose, etc. However, despite all data the impact of pharmaceuticals on particular developmental stages, mortality, growth rate and postembryonic development of crayfish had not yet been fully explored. Therefore, we provide an overview about the known effects of pharmaceuticals on crayfish and demonstrate that these effects could be quite multifaceted.

 

 

POSTER 27

Eradicating Signal Crayfish with a Biocide: What Worked, What Didn’t

Peay S

In its introduced range in Europe signal crayfish Pacifastacus leniusculus has become invasive, with impacts on indigenous crayfish and other fauna. Where a new population is detected while it is still localised there is the potential to carry out a biocide treatment to try to eradicate the population. During 2004 to 2012 six treatments with natural pyrethrum have been carried out in Scotland and England, followed by intensive monitoring for five years to determine outcome. Results show there were two confirmed successes and one probable (after three years monitoring, ongoing) and three sites where complete eradication was not achieved. Treatments and relevant factors are outlined and key lessons learned.

 

 

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.