Natural and anthropogenic driving forces as key elements in the Lower Danube Basin-South-Eastern Carpathians-North-Western Black Sea coast area lakes: a broken stepping stones for fish in a climatic change scenario?

Background Climate changes influence the ecosystems and induce potential risks regarding the natural products and services; the human society should predict and adapt in time to these coming global challenges. This research highlights a possible fragmentation of some of the Lower Danube River Basin lentic ecosystems fish populations in a climate change scenario. Results The studied climate change potential events will affect 18 fish species of economic interest and eight of conservation interest and will induce disorder in some of the Lower Danube specific type of fish communities. The studied area was identified as a significant hot spot regarding the fish fauna ecological status major hazard, in a possible climate change (heating-drought-water depth decreasing) sequence of potential future events. Primarily the southern lakes of the studied area can be negatively influenced by the decreasing of the lakes water quality and quantity, some of the spawning habitats will vanish, some habitats and species will disappear, suspended sediment and nutrient levels in water will increase, eutrophication phenomenon will increase, the hydrological connectivity will diminish, fish associations' structure will significantly change, etc. Conclusions The climate changes trend in the Lower Danube Basin will affect the studied lakes ecological state and associated fish communities; mitigating measures are urgently needed. The future potential relative isolation of researched lakes by the surrounding hydrographical nets, for safety reasons of human communities or to convert inland areas should be banned specially for the lakes: Balta Domneasca, Razelm, Tabacarie, Siutghiol, Tasaul, Tatlageac, Sinoe, Potcoava, Snagov, Comana, Victoria Gheormane, Dunarea Veche, Oltina, and Bugeac. Some of the researched lakes should be managed as wetlands of international importance and as important stepping stone areas for the fish fauna of the Danube Basin: Snagov, Comana, Victoria Gheormane, Dunarea Veche, Oltina, and Bugeac.