In the Korean Peninsula's southern estuaries, the distributive characteristics of epilithic diatoms and the important environmental factors predicting species occurrence were examined. The collection of diatoms and measurements of water quality and land-use were performed every May between 2009 and 2016, with no influence from the Asian monsoon and snow. Throughout the study, 564 diatoms were classified with first and second dominant species of Nitzschia inconspicua and N. perminuta. Based on diatom appearance and standing crops, the 512 sampling stations were divided into four groups by cluster analysis, and two regions, namely the West and East Sea. Geographically, G1, G2, G3, and G4 were located in the East Sea, Southeast Sea, West Sea, and Southwest Sea, respectively. Canonical correspondence analysis (CCA) results indicated that environmental factors, such as turbidity, electric conductivity (EC), and total phosphorus (TP), significantly influenced the distribution of epilithic diatoms. A random forest model showed that major environmental factors influencing the diatom species appearance included EC, salinity, turbidity, and total nitrogen. This study demonstrated that the spatial distribution of epilithic diatoms in the southern estuaries of the Korean Peninsula was determined by several factors, including a geographically higher tidal current-driven turbidity increase and higher industrial or anthropogenic nutrient-loading.
Keywords: CCA; benthic diatom; cluster analysis; diatom indices; estuary; random forest.