The Effects of a Typhoon on the Dynamic of Microbial Community Structure and Water Quality of the Marine Bathing Beach

Dalian Jinshitan beach was chosen to evaluate the impact of a typhoon on the bacterial community structure and water quality of a marine bathing beach. The concentration of enterococci was determined by the cultivation method. The bacterial community structure and abundance were analyzed using the 16S rDNA next-generation sequencing and qPCR methods. Results showed that the abundance of cultivable enterococci both in alongshore and offshore seawater increased, while it decreased in dry, wet and submerged sand. The water quality deteriorated immediately after the typhoon, and nearly recovered one month after the typhoon. The typhoon event also decreased the bacterial abundance and changed the bacterial community of the beach. Sphingomonadaceae and Rhodobacteraceae significantly increased in seawater and decreased in dry sand immediately after the typhoon. Human and other fecal taxa increased in water and sand. One month after the typhoon, the diversity and many dominant bacterial taxa nearly recovered in seawater and wet sand. Our work shows that the typhoon changed the bacterial dynamics, deteriorated the water quality and proved the transportation of bacterial taxa and input of fecal pollution between water and beach sand or land. Apart from the impact of the typhoon, the geographical location was another important factor in the changed bacterial community.