Management Decisions Support System for Rhodeus Amarus (Bloch, 1782) Species Populations in Oltul Mijlociu – Cibin – Hârtibaciu Natura 2000 Site (Romania)

The main threats to the Rhodeus amarus (Bloch, 1782) populations in the Natura 2000 site Oltul Mijlociu - Cibin - Hârtibaciu are the hydro technical modifications of the riverbeds, chemical pollution and poachery. ADONIS:CE is used in general for modeling business processes, but here was used in ecology/biology domain. The authors obtained a Rhodeus amarus model which included all the habitat species requirements, the indicators that provide favourable conservation status and the existing threats and pressures. The maintaining of the minor riverbed morphodynamics is very important - the meanders presence is very important for the local molluscs which are living in the inner U shape parts of the river. The places, where the sediments (sand, mud) are relatively stable, provide suitable habitats for molluscs important for the breeding of Rhodeus amarus. The maintaining of the actual regimes of liquid flows and oxygenation, and the avoidance of increasing of the sediments deposition rate in the water are necessary also for those molluscs species presence conservation. The extraction of sediments in these rivers should be made in correspondence with their natural rate of refilling and at sites at a distance of minimum five kilometres from each other.