Investigations of Variability of Morphometric Characteristics in Stone Crayfish in Order to Preserve Autochthonous Genome

This paper presents the information about morphological variability and sexual dimorphism of the stone crayfish (Austropotamobius torrentium) in the area of Korana River in Mrkonjic Grad. The crayfish were caught by hand made baited traps from October 2018 to May 2019. A total of 46 crayfish were caught, of which 33 males and 13 females. The dimensions of eight morphometric characteristics: body weight (W), body length (TBL), rostrum length (ROL), rostrum width (ROW), claw length (CLL), carapace length (CPL), carapace width (CPW) and abdomen length (ABL), were analyzed, both in males and females. Also, the body condition was determined for all individuales. The measurements results of morphometric characteristics partially matched into the alredy known range of variations. These data presens first ones for the observed area. By using Mann-Whitey U-test, it was noted that there are significant differences between the sexes for W, TBL, CLL, CPL, CPW and ABL. These resuls could be explained by sexual dimorphism of the stone crayfish.

Crayfish chelae usage suggests predominantly ambidextrous habitude

Heterochely is an important feature in some marine decapod crustaceans, but it is seldom investigated in freshwater crayfish. In this study, we applied a biometrical analysis targeting wild populations of three European crayfish species, Astacus leptodactylus, Astacus astacus, and Austropotamobius torrentium, as well as one invasive North American species, Faxonius limosus. Field data were combined with video-recorded observations to understand the usage of chelae in laboratory experiments for A. leptodactylus and F. limosus. According to biometrical measurements, heterochely was evenly distributed between species and sexes in wild populations, leading to the assumption that there is no specific pattern in chela size. Moreover, we found that the ambidextrous usage of chelae is a commonly encountered behaviour in crayfish, since no significant relationship was found between their chelae and asymmetry. This behaviour could maximize the chances of survival for crayfish in general, since losing one or both chelae is often recorded in the wild.

Χαρακτηρισμός και ταυτοποίηση καραβίδων εσωτερικών νερών της ηπειρωτικής Ελλάδας

Στην Ελλάδα, απαντώνται τρία αυτόχθονα είδη καραβίδων των εσωτερικών νερών (Astacus astacus, A. leptodactylus και Austropotamobius torrentium) και ένα ξενικό είδος από τη Βόρεια Αμερική (Pacifastacus leniusculus). Στόχος της παρούσας διατριβής είναι ο γενετικός χαρακτηρισμός και η φυλογενετική και φυλογεωγραφική ανάλυση των ειδών καραβίδας στην Ελλάδα. Για την διεκπεραίωση της μελέτης, πραγματοποιήθηκαν συστηματικές και εκτεταμένες δειγματοληψίες στην ηπειρωτική Ελλάδα. Η διερεύνηση της γενετικής δομής και ποικιλότητας των καραβίδων πραγματοποιήθηκε κάνοντας χρήση μιτοχονδριακών γονιδίων (ενίσχυση τμημάτων των 16S και COI γονιδίων). Αναλυτικά παρουσιάζονται τα αποτελέσματα που προέκυψαν από τη χρήση βιοπληροφορικών εργαλείων (προγραμμάτων και γλώσσας προγραμματισμού). Διαπιστώνεται μια πολύπλοκη και ανεξάρτητη μικρο-εξέλιξη των αυτόχθονων καραβίδων. Συγκεκριμένα, φαίνεται ότι τα Βαλκάνια έπαιξαν σημαντικό ρόλο στην φυλογεωγραφία των Astacus astacus και Austropotamobius torrentium. Στο Astacus leptodactylus παρατηρείται γεωγραφική ασυνέχεια μεταξύ των απλοτυπικών ομάδων. Ταυτοποιείται για πρώτη φορά το αλλόχθονο είδος Pacifastacus leniusculus στην Ελλάδα. Επιπλέον, η χρήση έξι μικροδορυφορικών δεικτών, επέτρεψε τη μελέτη του πολυμορφισμού, της δομής και της δημογραφικής ιστορίας του Astacus astacus στην Ελλάδα. Βασιζόμενοι στα αποτελέσματα της παρούσας διατριβής, γίνεται συζήτηση των πιθανών αιτιών (γεωλογικών, κλιματικών και υδρολογικών φαινομένων) που συνέβαλαν στην παρατηρούμενη γενετική δομή και ποικιλότητα των καραβίδων. Διαπιστώνεται, επιπλέον, ότι η κατανομή και η γενετική δομή των ειδών επηρεάστηκαν και από ανθρώπινες παρεμβάσεις (δηλαδή μεταφορές πληθυσμών καραβίδας από τον άνθρωπο).

Recent changes in distribution pattern of freshwater crayfish in Croatia − threats and perspectives

Analysis of Croatian freshwater crayfish populations, aiming to gather new distributional data and complement previous surveys (2005–2011), was performed during 2014–2016, within the frame of Natura 2000 Integration Project. The research included different waterbodies across the whole of Croatia, harbouring both indigenous and non-indigenous crayfish species (ICS and NICS, respectively). Field work was conducted in 117 grid squares with dimensions 10 × 10 km, and up to four waterbodies were surveyed per grid square, making a total of 450 studied sites. Out of those, crayfish were not recorded in 368 sites. In the sites with crayfish presence (i.e., 82), the most frequently observed ICS was Astacus astacus (registered in 33 sites) followed by Austropotamobius pallipes (16 sites), Austropotamobius torrentium (12 sites), and Astacus leptodactylus (5 sites). Concerning NICS, the majority of records were for Orconectes limosus (13 sites), followed by Pacifastacus leniusculus (2 sites), whereas Procambarus fallax f. virginalis was registered in only one locality. Comparisons of obtained data with those from previous surveys showed that NICS are progressively spreading and displacing ICS, as recorded for A. leptodactylus that was almost completely displaced by O. limosus in waterbodies of the east Croatia. Existing ICS populations are under growing anthropogenic preassure, frequently fragmented and isolated. Moreover, this survey showed that in the last decade 55% of A. astacus and 67% of A. pallipes populations disappeared mainly as a consequence of anthropogenic influence onto their habitats. Further monitoring and conservation actions for ICS should be urgently applied to mitigate negative impacts of both NICS and anthropogenic influence.