title: The Lower Danube River-Danube Delta-North West Black Sea: A pivotal area of major interest for the past, present and future of its fish fauna--A short review.
abstract: The complex Danube-Black Sea geoecosystem, created by a unique combination of integrated biotopes and biocoenoses related forces and counter-forces in time and space, forms a rich "ichthyosystem". The equilibrium among the fish species captured in the Danube Delta reveals its structural and functional roles in the connectivity of the Danube and Black Sea. The key role of the delta is evidenced by the fact that 57.26% of the Lower Danube-Danube Delta-North West Black Sea fish species use two or three of the subsystems in terms of habitats. Therefore, this convergence area can be considered to be a dynamic and rich "ichthyosystem", with three subsystems. All three evolved interdependently, which permits their flexibility and adaptation in an interdependent way. The habitat heterogeneity, native economic and conservation priority fish species of the Lower Danube-Danube Delta-North Western Black Sea have decreased significantly, and there are no indications that this trend will be halted soon. The Danube "sub-ichtyosystem" seems to be more directly affected than the others. The Lower Danube-Danube Delta-North Western Black Sea "ichthyosystem" exhibits a significant level of flexibility, resilience and adaptation over geological time, but has become much more sensitive to environmental perturbations due to the last century of human impact. This "ichthyosystem" is affected by non-native fish species. The study area represents an interdependent ecological net, without which the specific "ichthyosystem" formed over geological time will disappear. The studied ecological net fish fauna is an accurate indicator of various human pressures. The Lower Danube-Danube Delta-North West Black Sea geoecosystem, in which the Danube Delta provides the pivotal habitat element, is the matrix for a unique "ichthyosystem." However, human impacts decrease its resilience and can induce its extinction.
authors.affiliation: "Lucian Blaga" University of Sibiu, Faculty of Sciences, Applied Ecology Research Centre, 5-7 Dr. I. Raţiu Street, Sibiu 550012, Romania. Electronic address: ad.banaduc@yahoo.com.
authors.forename: Doru
authors.initials: D
authors.lastname: Bănăduc
authors.affiliation: School of Natural Sciences, Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, Scotland, UK. Electronic address: sonia.reyplanellas@stir.ac.uk.
authors.forename: Sonia
authors.initials: S
authors.lastname: Rey
authors.affiliation: Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of Sciences, 1 Tsar Osvoboditel Blvd., Sofia 1000, Bulgaria. Electronic address: trichkova@zoology.bas.bg.
authors.forename: Teodora
authors.initials: T
authors.lastname: Trichkova
authors.affiliation: Institute for Biological Research, University of Belgrade, 142 Bulevar Despota Stefana, Belgrade 11000, Serbia. Electronic address: lenhardt@ibiss.bg.ac.rs.
authors.forename: Mirjana
authors.initials: M
authors.lastname: Lenhardt
authors.affiliation: "Lucian Blaga" University of Sibiu, Faculty of Sciences, Applied Ecology Research Centre, 5-7 Dr. I. Raţiu Street, Sibiu 550012, Romania. Electronic address: angela.banaduc@ulbsibiu.ro.
authors.forename: Angela
authors.initials: A
authors.lastname: Curtean-Bănăduc
mesh_terms: D000818:Animals; D059038:Black Sea; D017753:Ecosystem; D004784:Environmental Monitoring; D005399:Fishes / Q000145:classification* / Q000254:growth & development; D014876:Water Pollution / Q000706:statistics & numerical data*
keywords: Geoecosystem; Ichthyosystem; Spatial dynamics; Temporal trends