Bloom forming species transported by ballast water under the management of D-1 and D-2 standards—Implications for current ballast water regulations

Abstract

Ballast water (BW) is a well-known transporter for introducing non-indigenous aquatic organisms. To reduce such risks associated with BW discharge, the International Maritime Organization (IMO) adopted the International Convention for the Control and Management of Ships' Ballast Water and Sediments (BWM Convention). We examined the abundance and diversity of bloom forming species in BW under the management of Regulation D-1 Ballast Water Exchange Standard and D-2 Ballast Water Performance Standard. The abundance and richness of bloom forming species were also examined in relation to ballast water age. Our findings indicate the abundance and diversity of bloom forming species were significantly lower in BW under the management of D-2 standard than that under D-1 standard. The abundance and richness represent no statistically significant correlation with BW age (p = 0.76 and p = 0.43, respectively). Some resistant species persist in ballast water. Thereby, we further provide some advice to overcome the existing challenges for the implementation of the Regulation D-2.