Abstract: Macrozoobenthos play a pivotal role in the biogeochemical cycling of C, N, and P in nearshore marine ecosystems by nutrient retention and recycling. To maintain the dynamic equilibrium in elemental contents, zoo-benthos must get a balance with their resource supply or alter their stoichiometric characteristics in response to environmental changes. We investigated the ecological stoichiometric characteristics of six macrozoobenthos species, including bivalve (Moerella jedoensis, Nitidotellina minuta, Mizuhopecten yessoensis) and ophiuroidea (Amphioplus japonicus, Ophiura sarsii vadicola, Ophiopholis mirabilis), which were collected from the coastal waters of Dalian Island in the northern Yellow Sea in May and August 2020. Results showed that the range of C, N, and P contents in the six species was 23.4%-49.8%, 4.3%-14.7%, and 0.1%-1.1%, respectively. The range for C:N, C:P, and N:P was 3.12-6.75, 29.01-410.63, and 6.32-113.9, respectively. The P content exhibited a relatively larger range of variation than C and N, leading to higher variability in C:P and N:P. There were significant differences in element contents and ratios between the two groups, bivalve and ophiuroidea. The stoichiometric characteristics of the three shellfish species under bivalve was significantly different in N content, C:N and N:P, while the three ophiuroidea species had significant differences except for C content, indicating that the ecological stoichiometric characteristics of marine macrozoobenthos had interspecific differences. The ecological stoichiometric characteristics of the same group and species were not significantly different between the two months. There was a significant correlation between the stoichiometric characteristics of macrozoobenthos, except for C content and P content, C content and C:P, N content and C:P.

Key words: ecological stoichiometry, bivalve, ophiuroidea, northern Yellow Sea