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LIST OF MEETING ABSTRACTS

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Oral | Posters

Oral Presentations

 

 

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.

 

Poster Presentations

 

 

POSTER 4

PIT Tagging Effect on Noble Crayfish (Astacus astacus L.) Survival

Kaldre K and T Paaver

A laboratory experiment was conducted to assess the potential impacts of 1.5 X 7 mm passive integrated transponder (PIT) tags on survival of noble crayfish (Astacus astacus L.). 30 noble crayfish (mean TL 96.9 ± 4.4 mm, 26 females and 4 males) were internally implanted with PIT tags and were kept together with untagged (as control) 30 crayfish (mean TL 96.0 ± 5.4 mm, 23 females and 7 males) in three 1 m³ tanks (10 tagged and 10 untagged crayfish in each) and maintained for 219 days at room temperature with a light regime of 16 h: 8h LD. 31 noble crayfish originated from a natural lake and 29 noble crayfish originated from a crayfish farm. 90% of tagged crayfish and 77% of untagged crayfish died during the experiment. The highest survival rate (30%) was observed in the third tank where the mean TL (93.4 ± 4.9 mm) was smaller than in the first (97.6 ± 3.0 mm) and in the second tank (98.5 ± 5.0 mm) where the survival rates were 10%. All survived crayfish originated from the crayfish farm. We can assume that smaller crayfish tolerate tagging better and the farmed crayfish survive better than wild ones.

 

 

POSTER 6

Epifauna on Freshwater Crayfish (Crustacea: Decapoda) in Croatia

Dražina T, Maguire I, Korša A, Špoljar M and Klobučar G

The crustacean exoskeleton is well known substratum for associate species - epibionts. During 2014 and 2015, we have studied epifauna on six different freshwater crayfish species collected from continental and mediterranean regions of Croatia (Europe). Four of them are autochthonous (Astacus astacus, Astacus leptodactylus, Austropotamobius pallipes, Austropotamobius torrentium) and two allochthonous invasive species (Pacifastacus leniusculus and Procambarus fallax f. virginalis). The epibiont samples were collected from the exoskeleton surface and from the crayfish gill cavity. The aims of this research were: (i) to analyse epifaunal assemblage on different freshwater crayfish and (ii) to compare epifauna among different crayfish populations, especially between autochthonous and allochthonous species. A total of 44 different epifaunal taxa were recorded. The most abundant group was Ciliophora, with Vorticella campanula and Epistylis sp. as the most frequent taxa. Rotifera was the most diverse group and 16 different taxa were identified. Four rotifer species (Lepadella astacicola, L. branchiola, L. parasitica and Dicranophorus hauerianus) were determinated as specific inhabitants of certain crayfish species and these rotifers were found exclusively on autochthonous species. Branchiobdellidans were constant crayfish epibionts, and for the first time the North American species Xirogiton victoriensis has been recorded in Croatia. Representatives from Catenulida, Gastrotricha, Nematoda, Bivalvia, Hirudinea, Tardigrada, Crustacea, Hydrachnidia and Chironomidae were also recorded as epibionts on freshwater crayfish. Results of this study suggested the separation of epifaunal assemblage between autochthonous and allochthonous crayfish, as well as the separation of epifauna among autochthonous species. Our results indicate highly diverse, complex and specific epifaunal assemblage on different crayfish populations. Thus, multiple relationships between crayfish host and epibionts will be the topic of further studies.

 

 

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 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 19

Invader showdown: interference competition between Orconectes immunis and Pacifastacus leniusculus

Wendler F and Chucholl C

Alien crayfish are among the most damaging invaders of European inland waters and changes in the crayfish fauna should be monitored prudently. Here, we investigated for the first time direct aggressive interactions and competition for shelter between alien calico crayfish, Orconectes immunis, and signal crayfish, Pacifastacus leniusculus, which are highly invasive in Central Europe. Specifically, we monitored bouts of interspecific 1:1 combinations in laboratory experiments and offered limited shelters in a similar setting. In size- and sex-matched combinations, O. immunis won significantly more interactions than P. leniusculus; however, O. immunis females were inferior to size-matched P. leniusculus males. Similarly, P. leniusculus males were dominant over 4 mm smaller O. immunis males in chelae size-matched bouts. Both species showed a similar affinity to the provided shelter, but O. immunis was dominant in the shelter competition experiments in both sexes. The dominance of O. immunis males in size-matched combinations may be related to their greater 'resource holding potential' due to larger chelae size than P. leniusculus males. Orconectes immunis females, however, featured similar sized chelae than size-matched P. leniusculus females, and their dominance can best be explained by higher inherent aggression of O. immunis. Based on these results, O. immunis can be expected to outcompete similar sized P. leniusculus. However, since the latter invader grows considerably larger than O. immunis, and gained dominance at a size advantage of 4 mm, outcomes of interactions in the field may be much more complex, presumably also due to contrasting life-history strategies.

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