Scientific Annals of the Danube Delta Institute (Sep 2012)
New data concerning fish fauna from lakes of the fluvial Danube Delta (Gorgova-Uzlina and Sontea-Furtuna lake complexes, Romania) in 2010
Abstract
New data refers to evolution of ichthyofauna in last decade, especially after first record of Amur sleeper (Perccottus glenii) in DDBR in 2007. Two complexes were investigated in August 2010, using two complementary sampling-methods: electric fishing for shore areas and gillnet fishing for deep water zone. These studies improve the knowledge on fish fauna in the area after visible human influences in the 80’s and 90’s (water pollution, eutrophication, uncontrolled fishing, poaching etc.), contributed to quantitative decrease of native fish species, which suffered important structural and quantitative changes. The waters of this complexes shelter fish communities that include 37 species over time, with 6 exotic fish species (the most important scientific discovery for the last few years in Danube delta is the occurrence of Perccottus glenii). Out of the total number of captured fish species (37), in 2010 were captured 32 species (last sampling in 2010 increased fish diversity with 3 species – Atherina boyeri, Hypophthalmichthys molitrix and Leuciscus idus). The most abundant fish species in 2010 are Alburnus alburnus, Rutilus rutilus and Scardinius erythrophthalmus, but in biomass dominant are Scardinius erythrophthalmus, Perca fluviatilis, Rutilus rutilus and Carassius gibelio with differences for those twocomplementary methods of sampling. Regarding to biodiversity index and equity indices of the ichthyofauna is noticed that thelake-complexes have a medium stable ecosystem, but Shannon-Wiener index is lower than in others campaigns of sampling (like was in 2004, 2007). The main species for ecological significance index is Alburnus alburnus, and Perccottus glenii is not anymore an accidental species (like it was in 2007).
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