Native species
Austropotamobius torrentium
racul-de-ponoare
Stone Crayfish
Steinkrebs
écrevisse des torrentsracul-de-ponoareStone CrayfishSteinkrebsécrevisse des torrentsCrayfish that rarely exceeds 10 cm in total length. The carapace is smooth and the dorsal colour varies from dark brown to light orange or even white, depending on several factors (including time since last moulting, age, and habitat characteristics). The ventral side is lighter, almost creamy-white, more intense on the ventral surface of the claws. The rostrum is shaped like an isosceles triangle — smooth with thin margins and a short apex compared to the Noble Crayfish. There is only one postorbital ridge, without spines. The cervical groove is smooth. The claws are relatively strong, similar to those of the Noble Crayfish but with shorter fingers. The propodite has a median cavity flanked by tubercles, and the dactylpodite has a single tubercle in the proximal third.
Native species, it occupies a narrow range in central and southern Europe, with its genetic centre in the Dinaric Mountains. The northern limit reaches Germany and the Czech Republic; to the west it extends to Luxembourg and eastern France; to the east as far as Romania and Bulgaria; and to the south into Greece and even Turkey (Souty-Grosset et al. 2006). In Romania its distribution covers the montane and submontane zone of the south-west, up to the Jiu Valley. For the distribution map, visit the distribution page.
Males often have longer and stronger claws than females, and the abdomen is visibly broader in females. To precisely distinguish the sexes, especially in juveniles, one should examine the sternal plate and the pleopods. Male crayfish have the first two pairs of pleopods strong and oriented anteriorly (for spermatophore transfer), while in females all pleopods are equal. The shape of the first two male pleopods is an important criterion for distinguishing it from similar species: the first pleopod (Pl. I) has a distal lobe almost 1/2 of the total length, while the second pleopod (Pl. II) has an exopodite no longer than 2/3 of the endopodite length, the distal lobe of the endopodite being approximately 1/2 of its length.
The preferred habitat is pristine running water (springs and brooks), though it can also be found in rivers or even mountain lakes. Contrary to its common name it is not a species characteristic of underground waters, though it can reach such habitats during floods. It typically digs galleries in earthen banks but is frequently found hidden under submerged roots, stones or rocks. Mostly nocturnal, it consumes almost any food — a true sanitary of the waters. Juveniles feed predominantly on animal matter (aquatic macroinvertebrates) while adults eat mainly plant material and fallen deciduous leaves. Highly sensitive to oxygen deficiency and chemical pollution; in villages where traditional washing is carried out in river beds, populations may suffer massive losses from detergents. Stream channelisation and urbanisation of submontane areas represent a major threat. Natural predators include fox, wolf, bear and badger (adults), while fish are the main threat to juveniles. The expansion of North American crayfish introduced to Europe is a serious concern — Pacifastacus leniusculus can eliminate an entire population within 4–5 years. The oomycete Aphanomyces astaci, introduced alongside North American species, causes crayfish plague, a disease to which native species have no resistance.
Stone Crayfish mate in autumn, at the end of October, before the waters freeze. During this period white spermatophores can be observed on the sternal plate of the female. The clutch contains 40–70 eggs (rarely up to 100) and is carried by the female among the pleopods until the juveniles become independent. For appropriate embryonic development water temperature should not exceed 5°C. Survival rates range widely, from 10 to 70% of the total clutch. Moulting is more frequent in young animals (up to 4–5 times per year); adults moult once or twice a year, usually between May and July. The few days following a moult are critical: without the protection of the hardened exoskeleton the crayfish can be easily attacked by fish or by other individuals. Lost appendages can regenerate during moult but usually reappear smaller. Sexual maturity is reached at 3–5 years, at a total length of 35–50 mm. Males can fertilise eggs every year while females may remain sexually inactive for one or more years after a laying.
