The Variation Of Plankton Species And Abundance In Ballast Water And Sediments

Since the International convention for the control of ships ballast water and sediments will be implemented, the ballast water management systems and ballast water treatment technologies has aroused extensive concern in the international community. As an important aspect in basic research, seldom studies have yet been carried out on the en-route investigations of species and abundance of plankton in ballast water and sediments, especially for the voyages starting from ports in China. This study, which supported by National Key Technologies R&D Program (Project No.2006BAC11B04), perform the following investigations:Investigate the species and abundance of plankton in four routes-Shekou to Ras Tanura, Dalian to Xiamen, Dalian to Haikou and Haikou to Dalian. Also investigate the species and abundance of phytoplankton, especially the cysts species and abundance, in ballast water sediments of ten ocean vessels. The variation of resting cells- resting spores and cysts abundance in ballast water and sediment were first investigated. The results showed that:The species and abundance of plankton in ballast water and sediments was mainly related with the area which the ballast water ballasting. The species and abundance of plankton in ballast water and sediments in different routes was different. The species and abundance of plankton in ballast water and sediments also different in same routes which ballasting in different seasons.When the ballast water age was longer than four days, the abundance of plankton in ballast water will decrease significantly, which along with little increasing during the decrease. If the routes were within four days, meanwhile the temperature in ballast water tank was increasing, the abundance of plankton in ballast water will unnotable decrease. The plankton species in international route show more invasion tendency then domestic route. However, the potential destroy of ecological balance on plankton species composition were should be emphasis. A lot of phytoplanktons could survive by changing the vegetative cells into rest cells. Once these rest spores or cysts arrived destination with ballast water, might bring potential destroy to that area. Based on the variation abundance of plankton, we found that temperature was one of key factors which lead to suddenly increasing of rest cells. And with suddenly change of temperature, especially temperature decreased will lead to the decreased of zooplankton abundance. Not all ballast water and sediments contain rest cells of phytoplankton, and not all phytoplankton in ballast water will form rest cells, which means the forming process of rest cells in ballast water tank was a complicated process. The nutrition factors especially nitrate and ammonium contents have significant correlation with Chla, and phosphates contents also significant correlated with phytoplankton biomass, which indicated that the nitrogen and phosphorus were also the mainly key limiting nutrition factors in ballast water tank.