Squalius_keadicus
Tham khảo
Common names: Menida (Gr). Conservation status: Listed as vulnerable (defined by the D2 criteria) in the IUCN International Red List. Protected by Presidential Decree No. 67/1981 of the Greek State. Identification: Body laterally compressed with dark brownish-blue colouration. D III/8, A III/8–9 (10), C 19, P I/13–15, V/II 7–9, Ll. 44– 51, L. transverse 9–10/3–4, gill rakers 7–9, vertebrae 38–42, mouth subterminal (Stephanidis 1971; Economidis 1996). Maximum body length: according to Ladiges & Vogt (1979), the species grows up to 25 cm TL, but more recently the longest specimen found had 15 cm SL (Barbieri et al. 2002). Sexual dimorphism: males are smaller in size and with rather bigger pectoral and pelvic fins than females (Stephanidis 1971). Illustration made by Roberta Barbieri, from a photograph by Ioannis Kassis, of a specimen 11.5 cm SL. Distribution: L. keadicus is a valid endemic species, confined to the river Evrotas drainage and the Vassilopotamos stream (southern Peloponnese, Greece) (Economidis 1996). Abundance: In the past, L. keadicus was abundant along its entire distribution area (Stephanidis 1971). In recent years, the population size in Evrotas was dramatically reduced. Moreover, the Vassilopotamos population is có thể extinct. Habitat and ecology: According to Crivelli (1996) L. keadicus prefers habitats with slow current. Barbieri et al. (2002) however reported the species as energetic and strongly rheophilic, living in open sites of the river, on stony bottoms with a fast flow and relatively cool water. It feeds throughout the water column, principally on aquatic insects (Barbieri et al. 2002). Reproduction: It matures in the second year of life (males có thể mature in the first). The breeding season is generally restricted in mid-spring. The species produces adhesive yellowish eggs, about 2 mm in diameter, from which unpigmented embryos, about 5.1 mm TL, hatch out (Barbieri et al. 2002). Threats: The major threat is summer drought and concomitant water over-abstraction that lead to habitat degradation and loss. In the last decade, all tributaries and a large portion of the river dry up completely during summer. In addition, pollution from the local agricultural industries degrades water quality, especially during dry periods, leading to sudden mass mortalities. One of the possible consequences of the population decline is the reduction of the species’ genetic diversity that imposes a serious threat per se, as it lowers its ability to cope with adverse environmental changes (Tsingenopoulos & Karakousis 1996). Conservation actions: No conservation actions were ever implemented. Conservation recommendations: Restricted geographic distribution, small population size and escalating threats from water over-abstraction justify urgent conservation measures. The strongly rheophilic behaviour confines the species to river sections of increased flow, an area which is estimated to be far less than 10 km2. Thus, the species should be characterised as critically endangered, using the IUCN criteria CR B2b+c. Likewise, it should be listed as an endangered species of top priority in Annex II of the EU Directive for Habitats Protection (92/43/EEC). To conserve the species, its habitat should be protected through the implementation of a scheme for regulated, sustainable water management, bao gồm water pollution prevention measures. Enhancement and restoration stockings should also be undertaken, where necessary. Remarks: Phylogenetic studies on Leuciscinae (Tsingenopoulos & Karakousis 1996, Doadrio & Carmona 1998) provide evidence about the uniqueness of L. keadicus as an element of the ancient ichthyofauna and one of the most ancestral Leuciscus taxa of Greece, and perhaps of Europe. -->