The negative impact of salinity was similar to that observed in the Kuroshio (Kodama et al., 2021). In June 2010, the δ15NPOM in the surface less-saline Changjiang diluted water (at 5 m depth and salinity <30) was recorded to be ~9‰ in the northern part of the ECS (Sukigara et al., 2017). In 2011, the δ15NPOM in the Changjiang diluted water in 2011 was ~6‰ (Sukigara et al., 2017). Sukigara et al. (2017) stated that POM with high δ15NPOM was not always present in the Changjiang diluted water, although high δ15NPOM was also reported in the ECS in previous studies (Gao et al., 2014; Wu et al., 2003). These findings corroborate the hypothesis that high δ15NPOM levels originate from the less-saline Changjiang diluted water that mainly flows into the SOJ during the summer (Morimoto et al., 2009), as well as the negative relationship between salinity and δ15NPOM.