Abstracts
IAA21 Book of Abstracts (PDF)
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LIST OF MEETING ABSTRACTS
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Oral Presentations
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: 4, Session: 3, Talk: 2
White-clawed Crayfish (Austropotamobius italicus, Faxon) Effects on Macroinvertebrate Communities from Mediterranean Limestone Mountain Streams
Juan Antonio Arce, Alonso F, Camacho A and Rico E
The white-clawed-crayfish was well widespread over most of drain basins from the Iberian Peninsula in the past, but habitat destruction and exotic species-mediated diseases put it at risk of extinction during last decades, being remnant populations restricted to headwaters and small tributaries. Crayfish are generally recognized as omnivores, displaying an opportunistic foraging behavior on steam biota, among which macroinvertebrates play a main role. To better understand A. italicus interactions with benthic macroinvertebrate headwater communities we designed a field study in a permanent mountain stream from Central Spain, where three-month mesocosm-based experiments were carried involving crayfish densities usual in nature. Neither positive nor negative impacts of A. italicus on macroinvertebrates were evident in terms of richness, abundance and biomass, although some particular taxa resulted affected. Upstream recolonization, drift processes and particular evasiveness traits of many taxa were proposed as main compensation mechanisms displayed by macroinvertebrates to keep stable populations along time under theoretical crayfish predation. As a whole, and together with the absence of impacts on epilithic algae showed by previous studies, A. italicus should not be considered as a bioturbator agent in compositional, structural and functional terms for limestone headwaters. Therefore, restocking actions involving this species in suitable water courses are recommended, presumably not posing a risk on local benthic communities.
Poster Presentations
POSTER 2
Crayfish Epibionts Branchiobdella sp. on the Stone Crayfish in the Czech Republic
Vlach P and ŠrámkováL
This contribution evaluates the occurrence of crayfish epibionts Branchiobdella inhabiting stone crayfish in the Czech Republic. The study was conducted in 8 localities (from app. 40 known localities), respecting its natural range in the country. In total, we determined 723 individuals of 4 species: Brynchiobdella pentodonta,/i>, B. hexodonta, B. parasita and B. astaci. B. pentodonta dominated (403 ind.) in the whole sample, and also B. parasite,/i> occurred frequently (316 ind.). On the other hand, B. hexodonta was recorded only three times and B. astaci only once in the left tributary of Novosedlský brook in Upper Palatine Forest. The most variable locality was Huníkovský brook with 3 recorded Branchiobdella species - B. parasita, B. pentodonta and B. hexodonta, whose occurrence was recorded only in this stream. B. parasita was mostly the dominant species, or occurred equally to B. pentodonta in the stream Chýlava. On the contrary, in Zubrina, the abundance of B. pentodonta prevailed. The highest abundance of Branchiobdella sp. was recorded in Zubrina (17 ind. per one crayfish on average), conversely the lowest number in Medvedí brook was observed (0.3 ind. per crayfish). Moreover, we found out that B. pentodonta significantly preferred its position on crayfish chelae, whereas B. parasita inhabited the whole crayfish body equally, except for chelae. The last findings could correspond with interspecific competition between both species.
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 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 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 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 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 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 15
Reproductive Cycle of the Marble Crayfish from an Established Population in Croatia
Cvitanić M, Hudina S and Maguire I
The marble crayfish (Procambarus fallax f. virginalis) is a relatively new non-indigenous crayfish species that has established populations in Europe. Until today, it is the only known decapod species with parthenogenetic reproduction. Established population of marble crayfish was recently discovered in a gravel pit in Northwest Croatia. Apart from parthenogenetic reproduction, the invasion success of this species stems from its early maturation, and higher fecundity compared to other crayfish species. Therefore, the aim of this study was to examine the year cycle of the marble crayfish in Croatia, and its potential (number of ovarian eggs) and realized fecundity (number of pleopodal eggs and juveniles). Our results show that all 140 examined individuals were reproductively active during the whole sampling period. Peaks of reproduction activity were recorded from September to November, when both individuals with pleopodal eggs or juveniles as well as individuals with ripe ovarian eggs were recorded. The smallest reproductively active female was 40.81 mm TL, while reproductive output increased with size (TL). The average number of ovarian eggs was 297. The average number of pleopodal eggs was 15% lower than the number of ovarian eggs, while number of juveniles attached to pleopods was reduced by 50% from ovarian egg count. This represents a lower brood loss compared to other crayfish species. Due to almost constant reproduction, early maturation and relatively high potential and realized fecundity in an established population in Croatia, the marble crayfish represents a major threat to the surrounding waterbodies and their native crayfish fauna.
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 18
No Species Recognition Between Two Alien Crayfish Species?
Tricarico E, Coignet A and Souty-Grosset C
Crayfish rely on odours for finding a resource, detecting predators and recognizing species. Species that are not co-evolved could not chemically recognize each other. The red swamp crayfish Procambarus clarkii and the spinycheek crayfish Orconectes limosus, both native to North America where they occupy different areas, have coexisted in the “Parc Naturel Régional de la Brenne” (Centre Region, France) since 2007 but in different ponds. Behavioural observations were conducted in October 2014 and April 2015 to assess if P. clarkii and O. limosus are able to chemically recognize individuals of both sexes belonging to the same or other species. In experimental individual aquarium, records of behaviour of 20 Procambarus males and 20 Orconectes males were made of 3-min observation bouts for each of two sequential phases: (a) the “water” phase, following the introduction of 10 mL of well water, (b) the “smell” phase, following the introduction of 10 mL of well water conditioned by (1) P. clarkii male, (2) P. clarkii female, (3) O. limosus male and (4) O. limosus female odour. The time spent by each crayfish in locomotion and other activities (feeding, cleaning), and the time spent in one of three postures (raised, intermediate, or lowered) were recorded every 15 s. Crayfish seem able to recognize the conspecific of the same sex (males), and not the heterospecific, underlying the absence of species recognition in these two species that separately evolved.
POSTER 23
Presence of Branchiobdellida in Five Population of Native Crayfish in Northern Italy: Preliminary Results
Fea G, Ghia D, Mazza L, and R Sacchi
Branchiobdellid annelids are commensal symbionts associated with crayfish populations, knowledge of their dispersion and distribution is generally scarce. The aim of this research was to identify the species of Branchiobdella isolated on the crayfish in different populations, and the prevalence among the species. We collected white-clawed crayfish Austropotamobius pallipes complex during the autumn 2013 from five creeks in Northern Italy. Worms were removed by inserting one-sidedly crayfish into a container with salty water (35 ppt): 1-minute each for claw, abdomen and cephalothorax; then branchiobdellids were placed into separate vials. The branchiobdellids identified, were Branchiobdella italica, Branchiobdella parasita, Branchiobdella astaci, Branchiobdella hexodonta and Branchiobdella pentodonta. We also found coexsistence of two or more species of Branchiobdella on crayfish at the same location. 46% of worms were present on abdomen and 40% cephalothorax while 14% were on claw. In all the populations studied at least two species of worms were detected and one crayfish was found to support four species of Branchiobdella.
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.
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.
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