Methodology for Identification of Areas with Possible Risk for Sturgeon Species Migration Disruption on The Lower Danube

Abstract

In the context of the continuing decline of the species belonging to the order Acipenseriformes on a global level, the anadromous sturgeon species sturgeon species in the Lower Danube have been affected by a significant reduction in historical migration routes and fragmentation of breeding habitats. This paper presents the stages of the methodology for identifying areas that present a possible risk of interruption of sturgeon migration in correlation with satellite images and daily values for discharge/water level databases. In order to determine the two ranges of values that characterize the extreme phenomena (high/low flows), a hydrological statistical analysis was carried out for the most extensive period of time covered by recorded data (January 2011 – May 2023) in the hydrometric station located in Calarasi, Romania. Based on the 4524 values from the series of average daily discharge values, the discharge hydrograph, the empirical curve of insurance/exceedance probability and the frequency and duration curves using 200 m3/s discharge steps were determined and represented. Correlated with satellite imagery recorded during the determined time intervals with extreme phenomena, there were identified areas with possible risk for sturgeon species migration disruption.