Year: 2026
Type: article
Abstract: Critically endangered Danube sturgeons rely on specific hydro-geomorphological conditions—such as deep riverbed pools and exposed hard substrates—for spawning, overwintering, and resting. However, continuous high-resolution riverbed maps across the Lower Danube remain scarce. This study provides a high-resolution bathymetric and substrate assessment of three key sturgeon habitats within the Danube Delta Biosphere Reserve: Balteni, Nufaru, and Isaccea (Noviodunum) in the Danube Delta Biosphere Reserve. Using a 500 kHz interferometric bathymetric sonar coupled with RTK-GNSS positioning and ADCP velocity profiling, we generated 1 m resolution Digital Terrain Models (DTMs) and mapped benthic substrates via side-scan sonar backscatter segmentation. Deep scour pools driven by bedrock steps were mapped at Balteni (35 m depth) and Nufaru (30 m depth), both hosting exposed hard-bottom substrates that function primarily as overwintering and resting refugia. In contrast, the Isaccea sector features a 17 m deep pool maintained by high flow turbulence over the submerged masonry of the ancient Roman fortress of Noviodunum, exposing a localized gravel-cobble substrate that acts as an active spawning ground. Our findings demonstrate that critical sturgeon habitats in the Lower Danube are highly localized micro-topographic anomalies, emphasizing the necessity of high-definition hydroacoustic surveys for targeted conservation and environmental impact assessments.
Language: English
Subfield: Nature and Landscape Conservation
Field: Environmental Science
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7204993417