2:45 PM - 3:00 PM
[HTT23-17] Food web analysis of Toyama Bay and seasonal changes of zooplankton: Using stable carbon and nitrogen isotopic ratios
Keywords:Stable isotope ratio, Toyama Bay, Zooplankton
Both on the analysis of these isotopic ratios, we reached the following findings. Aquatic creatures in Toyama Bay are located on a food web starting from POM and phytoplankton is the primary producer of both the shallow water and deep water creature. The δ13C values of zooplankton collected in Toyama Bay were higher than those from Yamato Basin. It is suggested that this is because the growth rate of the phytoplankton in Toyama Bay is faster than that in Yamato Basin. The δ15N in zooplankton depleted with the increase of the nitrate concentration in the surface seawater, and δ13C enriched with the increase of chlorophylla concentration in the surface water. Thus, it is considered that the δ15N value reflects the supply of nitrate and the δ13C value reflects the growth rate of phytoplankton.