POSTER 3

White-clawed Crayfish (Austropotamobius pallipes) Endangered Species Sampling Methods: Efficiency and Disruptions in the Balance

Olarte N, García-Arberas L and Alvaro A

The distribution of Austropotamobius pallipes in Biscay (Basque Country) is being increasingly restricted. After crayfish plague and the effects of many further threats, this specie is found in small headwater creeks away from the main streams. The species inhabits in small populations, generally isolated and fluctuating number of individuals. The main characteristic of these river stretches with a little flow is that they do not allow trap sampling methodology and so, other methods based on night viewing are used to get data to calculate population estimates. Two small rivers were sampled for 5 years. In this study, we have compared the values obtained by night viewing from river-bank (CPUEs) with manual searching on one pass (CPUEc). We have also correlated these methods with the estimate population size obtained by Removal method (ABUNDANCE). Both indirect estimates were highly correlated with ABUNDANCE, being stronger CPUEs-ABUNDANCE relationship (p=0.80; R2 =0.64) than CPUEc-ABUNDANCE one (p=0.67; R2 = 0.46). Night viewing is an acceptable strategy for population estimates without a direct interaction with the individuals. This strategy may optimize sampling, as it lets increasing the efficiency in effort and time and minimizing the perturbation generated with catching activity.

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 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 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 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 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.

POSTER 22

Positive Selection of Beautiful Invasives: Long-term Persistence and Bio-invasion Risk of Ornamental Crayfish

Chucholl C and Wendler F

Following a distinct peak interest to keep freshwater crayfish in home aquaria in the mid-2000s, the aquarium trade has become a novel introduction pathway for alien crayfish species in Central Europe. Here, we provide an update on the German ornamental crayfish trade approximately one decade after the `crayfish hype´ to explore the long-term implications in terms of bio-invasion risk. Specifically, species’ availability and potential invasiveness, as well as the determinants of availability were assessed. In July 2015, a total of 31 online shops offered 28 crayfish species, which represents a decline of 24% in species diversity compared to the late 2000s. In addition, the estimated rate of import of new species has considerably flattened and approaches pre-hype values (< 1 species · y^-1). However, the risk associated with the offered species, as assessed by a risk screening tool (FI-ISK), has not decreased compared to the late 2000s. Long-term availability in the trade (covering one decade) was primarily determined by bright coloration, the ability to reproduce under warm aquarium conditions, and a preference for lentic habitats. Species featuring such traits are likely to persist in the aquarium trade and include four high-risk species, most notably invasive and crayfish plague-carrying red swamp crayfish (Procambarus clarkii) and Marmorkrebs (Procambarus fallax f. virginalis). Persistent propagule pressure from aquaria has substantially contributed to the establishment of both species in Central Europe, stressing the need for effective pathway management.

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 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.