river before damming: distribution and ecological notes on the endemic species Echinogammarus cari (Amphipoda: Gammaridae) in the Dobra River and its tributaries, Croatia

• Published in: Aquatic ecology 2009-03, Vol.43 (1), p.105-115
• Main Authors: Žganec, Krešimir, Gottstein, Sanja
• Format: Article
• Language: English
• Subjects: Aquatic ecology; Biomedical and Life Sciences; Conservation; Dams; Drainage area; Ecosystems; Endangered species; Endemic species; Floods; Freshwater & Marine Ecology; Habitats; Hydroelectric plants; Life Sciences; Microhabitats; Mollusks; Mosses; Physicochemical properties; Relative abundance; Rivers; Streams; Tributaries; Water temperature
• ISSN: 1386-2588; 1573-5125
• DOI: 10.1007/s10452-007-9157-4

The endemic species Echinogammarus cari (Karaman 1931) is the only species of this genus present in the Black Sea drainage basin of Croatia. The species is known only from its type locality, the Bistrac spring. Since little is known about the distribution and ecology of this amphipod species, research was conducted to determine the extent of its distribution in the Dobra River and its tributaries, part of which will be flooded on the completion of a 52.5 m high dam in 2009. Sampling was conducted at 10 study sites in the drainage area of the sinking Gornja Dobra and at 19 study sites in the Gojačka Dobra, including measurement of physicochemical parameters. To examine microdistribution of this species, samples were collected on moss and on stony substrate. The species is confined to first 15 km of the Gojačka Dobra, its tributary streams Bistrica and Ribnjak, while it is absent in the drainage area of the Gornja Dobra. At all sites where it was recorded, it coexists with Gammarus fossarum, and its relative abundance was significantly higher on moss microhabitats, while G. fossarum was more abundant on a stony substrate. The downstream decrease in the relative abundance of E. cari could be related to the longitudinal decrease in conductivity and the increase of water temperature fluctuations. After the completion of the dam, 60% of the presently known distribution area of E. cari will be flooded. Consequently, the species is likely to become endangered.