Figure. 6. Differences in environmental parameters among the classes divided based on δ13CPOM and δ15NPOM. Parameters include (a) temperature, (b) salinity, (c) nitrate concentration, (d) chlorophyll-a concentration, and (e) C:N ratio. Box plots show the mean (thick horizontal lines within boxes), standard deviation (boxes), and maximum or minimum values (vertical bars). The small gray dots represent the raw values.