Cyanobacteria Bloom in the Azov Sea According to Landsat Data

Abstract

In this paper we studied the spatial and temporal characteristics of cyanobacteria bloom in the Azov Sea based on data from Landsat satellites sensors for 1999–2016. The strongest blooms were observed in 1999 and 2006–2009, when cyanobacteria occupied the entire central part of the Azov Sea. The maximal blooming in these years was in August–September. In 2006, cyanobacteria penetrated from the Azov Sea into the Black Sea through the Kerch Strait. The longest and most extensive cyanobacteria blooming is recorded in the Taganrog Bay, which is associated with its shallow water and the nutrient supply from the Don River. Here, blooms are observed from February to November. Local maximums of cyanobacteria accumulation are observed along the eastern coast of the Azov Sea, near the mouth of the Kuban and Protoka rivers, in the Akhtarsky estuary and in the Temryuk Bay. They are most rarely found near the northwest coast. The data from the Landsat series satellites sensors show that cyanobacteria spread from the Taganrog Bay to the south or west in summer. From the mouth of the Kuban River, cyanobacteria move north. An analysis of numerical calculations using the Nemo model showed that this distribution is associated with northern currents that occur in the southern part of the sea in summer due to the impact of river discharge. Maps of the probability distribution of the cyanobacteria observation were obtained and estimates of the seasonal variation of the area covered by cyanobacteria blooming were given according to the data from the Landsat series satellites sensors. In the Azov Sea, maximal blooming is observed in July–August and minimal blooming is observed in winter, from November to February.