Formation of Artificial Communities for the Ballast Water Management Systems Testing in Accordance with Requirements of International Maritime Organization

摘要

The International Maritime Organization (IMO) in the convention adopted in 2004 imposes stringent requirements on the quality of seawater used in the testing of ballast water management systems (BWMS). They concern both the abundance of plankton organisms of two size groups, 10–50 μm and more than 50 μm, and the taxonomic composition (at least five species of three taxonomic types). Marine phytoplankton has a wide variety of sizes and morphological forms of cells, which makes it difficult to apply the imperative size adopted by the IMO. It is proposed to formalize the size criterion by calculating an equivalent spherical diameter. The real test of the BWMS in 2017 set the task of assessing the compliance of natural water with these quality standards. According to the results of annual monitoring in the northeastern part of the Black Sea, it has been shown that the species diversity of phytoplankton in the size group of 10–50 μm always corresponds to the necessary requirements, but its abundance is two orders of magnitude lower than required. In this case, the simultaneous presence of representatives of three different systematic groups in the initial water is not always observed. This poses the task of modifying the hydrobiological parameters of ballast water by the addition of cultivated species and the formation of a new community with predetermined properties. In this work, we used an intense culture of green algae, which made it possible to increase the abundance of cells to the level corresponding to IMO requirements and also to add a representative of another taxonomic group. Taxonomic diversity in the size group above 50 μm is sufficient and is provided by species diversity of zooplankton; however, the contribution of these organisms to the total population is not large (no more than 3%). The necessary abundance of representatives of this size group was ensured by the cultivation of large dinoflagellates.