Abstract <p>The article examines and discusses the seasonal and spatial variability of dissolved organic carbon (DOC), apparent oxygen utilization (AOU), chlorophyll <i>a</i> (chl <i>a</i>), and the proportion of pheophytin in the sum of chl <i>a</i> and pheophytin <i>a</i> (pheo <i>a</i>) along a 5-mile transect opposite Golubaya Bay at stations with depths of 10, 25, 50, 100, and 500 m (Gelendzhik, northeastern Black Sea). Sampling was carried out in 2012 from April to November inclusive with a frequency of one to two times per month. Statistical analysis of the weight average concentrations of DOC and chl <i>a</i> calculated for the entire data set demonstrated a relationship between the seasonal dynamics of DOC and chl <i>a</i>. The Spearman correlation coefficient was <i>R</i> = 0.59 with <i>n</i> = 49. Analysis of the seasonal dynamics of the weight average concentrations of DOC and chl <i>a</i> at individual stations showed the highest relationship between the parameters at the station with a depth of 50 m (<i>R</i> = 0.85, <i>n</i> = 10), quite remote from both continental runoff and the influence of the Rim Current. No significant relationship was found between the temporal dynamics of DOC and pheo <i>a</i>. Considering that the concentration of chl <i>a</i> is an indirect characteristic of the abundance of active autotrophic phytoplankton and pheo <i>a</i> is an indicator of the physiological state of microalgae, it can be suggested that the biomass of autotrophic phytoplankton has a greater impact on the dynamics of DOC than its physiological state (activity).</p>