Diversity variation of zooplankton and phytoplankton communities in ship ballast water during the maiden voyage

Abstract

The transfer of ships' ballast water poses a risk of biological invasion to the aquatic ecosystem. Although the ecological risks posed by ships' ballast water have been reduced by the installation of type-approved Ballast Water Management System (BWMS) equipment, some treated ballast water still does not meet the requirements of the D-2 standard. Here, experiments were conducted to investigate the trends of phytoplankton and zooplankton in ship ballast water during different ship’s maiden voyages. The results showed that there are some differences in the trends of the abundance of zooplankton and phytoplankton in the ballast water samples of two ships, i.e., the “Zhang Jian” and the “Song Hang”. The abundance of zooplankton in the ballast water samples of the “Zhang Jian” showed an increasing and then decreasing trend. An explosion of phytoplankton, predominantly Chlorophyta and Cyanophyta, was observed in the ballast water samples of the “Zhang Jian” at the end of the voyage. The abundance of phytoplankton and zooplankton in the ballast water samples of the “Song Hang” showed a decreasing trend. The study aims to clarify the trends and composition characteristics of plankton in ballast water in different ships to promote the effective management of ballast water and protect the ecological environment of port waters.