A research note: Potential importance of N[formula omitted] fixers in the coastal northwestern East/Japan Sea

Abstract

Biological nitrogen (N2) fixation, a fundamental step in aquatic and terrestrial N cycles, is an important process through which “new” reactive nitrogen (N) is produced. The role of N2 fixation in fueling the occurrence of harmful algal blooms (HABs) is one of the major concerns in the present scenario. Since N2 fixation occurs under highly specific environmental conditions, determining the suitability of various ecosystems for potential N2 fixation is important. The introduction of 15N2 bubble experiments in 1995 has led to significant N2 fixation rate estimates from various parts of the world oceans; however, Korean coastal waters, which are prone to HABs, remained unstudied. The present study aimed to construct a research note on N2 fixation in the Korean coastal waters on the basis of a preliminary data set of N2 fixation rates (range; 0.31–2.35 nmol N L−1 h−1) obtained from the coastal northwestern East/Japan Sea. The results indicate that N2 fixation is not currently a significant N source in the northwestern East/Japan Sea. However, the possibility of N2 fixers being a future significant N source and a fuel for HABs in the East/Japan Sea under favorable environmental conditions cannot be ruled out.