Abstracts

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LIST OF MEETING ABSTRACTS

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Oral | Posters


Oral Presentations

 

 

Day: 2, Session: 3, Talk: 1

KEY NOTE: Natural Born Killers: The Oomycetes as Important Pathogens of Animals

Gordon Beakes

The oomycete “fungi” belong to the Straminipile/Alveolate/Rhizaria superkingdom and are closely related to the golden-brown algae. They used to be thought of as predominantly freshwater saprotrophs or parasites of plants. Over past two decades molecular phylogeny has radically altered the way we view the oomycetes. There are a number of early diverging, non oogamously reproducing, clades that contain mostly marine parasites of nematodes, crustaceans and seaweeds, many of which have extra-ordinarily elaborate infection structures. The Haliphthorales are important pathogens of crustaceans, that can result in significant losses in marine aquaculture systems. The major divergence in the oomycete lineage came with the splitting off of the Peronosporalean and Saprolegnialean lines. The former are largely terrestrial, often soil born or plant pathogens and are characterised by their periplasmic oogenesis (which requires exogenous sterols) and often vesiculate discharge of zoospores. The latter, encompass most of the familiar water mould genera, and include the basal Leptomitales and the more familiar Saprolegniales, that contain general such as Aphanomyces, Achlya and Saprolegnia. The Aphanomyces clade is particularly interesting as it encompasses clades that are predominantly animal pathogens (including A. astaci), plant pathogens and saprotrophs. It also includes several genera that parasitize invertebrates such as rotifers (Aquastella) and nematodes (Sommerstorrfia). The evolutionary equivalent in the Peronosporalean lineage appears to be the Pythiaceous clades that include pathogens of nematodes (Lagenidium, Myzocytiopsis), crustaceans (Salilagenidium) and vertebrates (Paralagenidium, as well as the more familiar saprotrophs and plant pathogens (Pythium spp.). The overall evolutionary significance of these findings will be discussed.

 

 

Day: 2, Session: 4, Talk: 2

Crayfish Plague in Japan

Martin-Torrijos L, Sandoval-Sierra J, Makkonen J, Jussila J, Kokko H, Kawai T and Javier Diéguez-Uribeondo

Crayfish plague caused by the oomycetous pathogen Aphanomyces astaci is chronically carried by a number of North American species of freshwater crayfish, such as Pacifastacus leniusculus and Procambarus clarkii. These two species have been previously introduced into Japan. The only native freshwater crayfish species of Japan Cambaroides japonicus is highly susceptible to this pathogen and has experienced a continuous decline during last decades. So far crayfish plague outbreaks have only been reported in Europe but in other regions of the world where chronic carriers’ have been introduced. In this, work we report the first case of crayfish plague in Cambaroides japonicus in Japan, which constitutes the first crayfish plague case reported outside Europe. Preserved samples in ethanol from an outbreak occurred in Hokkaido Island were histologically studied and analyzed using disease diagnostic ITS and mitochondrial DNA based primers. Phylogenetic analyses of the obtained sequences indicated that the A. astaci strain causing the outbreak belong to the PC phylogenetic lineage, and was most likely transmitted from Procambarus clarkii in inhabiting in the near vicinity.

 

 

Day: 4, Session: 1, Talk: 3

Low Local Crayfish Diversity and High Species Turnover in Lowland Streams may be Influenced by a Few Widely Distributed Crayfish Species

William R. Budnick, Harlan AR, Pasco TF, Kelso WE and Kaller MD

Crayfish are a numerous and diverse group of decapods that occupy multiple niches in lowland streams. However, the diversity of Louisiana crayfishes (~39 species) is poorly understood and is based on sporadic and voluntary reporting. Thus, average local diversity (a-diversity) and compositional turnover among localities (ß-diversity) have never been rigorously quantified or mapped. Herein, we quantify crayfish diversity using diversity indices, multiplicative hierarchical diversity partitioning, and variance in community composition among localities. Our data source from 59 wadeable streams in Central Louisiana sampled during summer 2013 and 2014 and span an area of approximately 24,000 km2 (~15% of state area), 5 major river drainages and 14 watersheds. Average a-diversity among all sites was characterized by low richness (typically 2-3 species) and extreme unevenness. Average a-diversity was typically lower than expected by random chance at drainage and watershed scales, whereas ß-diversity was typically greater than expected at both scales. Species turnover was the predominant beta diversity pattern at all spatial scales, but species loss (nestedness) increased relative to turnover at drainage and watershed scales. Finally, most variance in community composition resulted from variation in relative abundances of Procambarus clarkii,, Procambarus (Pennides) species, Orconectes lancifer, and Cambarellus puer. Our results suggest distributions and relative abundances of P. clarkii, O. lancifer and Procambarus (Pennides) species may play a deterministic role through competition and dispersal in diversity structuring of our study area. Future research will examine whether suppressed local diversity and enhanced turnover is a general feature of crayfish assemblages among lowland stream ecosystems.

 

 

Day: 4, Session: 2, Talk: 1

Do you Suffer from a Lack of Historic Crayfish Data?

Susan B. Adams

Do you suspect that a crayfish species was extirpated from your study area but lack the historic data to prove it was ever there? Do you lay awake at night wondering if a crayfish species is native or introduced to your study area, or wondering how long an introduced crayfish has been there? The answers to your questions may be waiting in your friendly, neighborhood fish museum. Recent work I conducted with colleagues demonstrated that fish guts may provide valuable information about crayfishes in large water bodies. Furthermore, in the USA, fishes have been collected and curated in museums more intentionally over much longer periods than have crayfishes. Therefore, a gold mine of historic crayfish data should be sitting in museums…in the guts of preserved fishes. I examined crayfishes from fish guts in museums to examine historic crayfish distributions where data from direct crayfish sampling were lacking. I will share what I found, the fishes and sizes that were most informative, and discuss both potential uses and disadvantages of the method.

 

 

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.

 

 

Day: 5, Session: 3, Talk: 3

Effects of Flood-control Impoundments on Community Assemblages of Stream Crayfish

Zanethia C. Barnett

Over half of the world’s rivers have seen changes in the magnitude and timing of flows due to water regulation and increased water usage, affecting the diversity and abundance of stream organisms. I tested whether flood-control impoundments altered crayfish assemblage up and downstream of impoundments in two impounded creeks (Little Bear and Cedar creeks) and one unimpounded creek (Rock Creek) northern Alabama, USA. Crayfish and fish were sampled and physiochemical variables were measured at 6 - 8 sites along each creek in 2015. Crayfish abundance and diversity (species richness) differed between impounded and unimpounded creeks, as well as up and downstream of impoundments. Catch-per-unit-effort (CPUE) of Orconectes validus was higher in Rock Creek than impounded creeks in both the spring and fall. Upstream of impoundments also showed higher CPUE of Orconectes erichsonianus than sites downstream. In Rock Creek, crayfish diversity at the site furthest downstream was significantly greater than at the three furthest upstream sites. There was no difference in the diversity at similar distances up and downstream of impounded creeks, except the furthest up and downstream sites in Little Bear Creek (p<0.05), with diversity being greater downstream. Fish predators of crayfish were significantly greater in impounded than unimpounded creeks. Water temperatures and percent dissolved oxygen were higher in impounded than unimpounded creeks. Turbidity was higher downstream than upstream of impoundments. Crayfish diversity and abundance in thousands of stream kilometers are being affected by dams, which will influence freshwater and riparian ecosystems by impacting the important functions that crayfish provide.


 

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 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 25

Photoperiod Affects Light/Dark Preference and Exploratory Behaviour in Noble Crayfish (Astacus astacus)

Abeel T, Platteaux I, Roelant E, Adriaen J and Vervaecke H

Artificial day-night cycles are known to affect crayfish growth, behaviour and physiological stress levels in aquaculture. Based on the protocol by Fossat et al. (2015), who validated decreased exploratory behaviour and raised photophobia as stress-induced anxiety-like behaviours in Procambarus clarkii, we evaluated the effect of different photoperiods on noble crayfish activity and light/dark preference in an aquatic plus maze. We kept 135 two-summer-old crayfish in a recirculating aquaculture system and exposed them to five different photoperiods: hours light/dark (L:D) 0:24, 8:16, 12:12, 16:8 and 24:0. All animals had access to brushes and PVC pipes as shelters. After 144 days, the crayfish were submitted to the plus maze test. During a ten minute period, each individual’s location was scored every five seconds. Exploratory behaviour was assessed by quantifying the number of movements between different locations in the maze. Light/dark preference was determined by the time spent in the dark or lit arms. A linear mixed model for the different outcomes was fitted using tank as a random intercept and treatment as a fixed effect. Crayfish kept in 24L showed a higher amount of movements (43.6±4.3 mean±stdev) than individuals from all other treatments (ranging from 30.9±2.4 in L16:D8 down to 23.3±3.3 in L12:D12, p=0.0004). They also spent more time in the lit arms of the maze (43.40±1.74%) than animals from the 24D treatment (25.07±4.22%) (p=0.040). These results show that continuous light stimulates exploratory behaviour and continuous darkness causes more neophobia towards lit areas.


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