Ecological stoichiometric characteristics of three dominant fish species from the Beibu Gulf: inter- and intraspecific variations

In this study we explore the inter- and intraspecific variations in the ecological stoichiometry of three dominant fish species [Saurida tumbil (n = 33), Pennahia macrocephalus (n = 34), and Upeneus sulphureus (n = 32)] from the Beibu Gulf, the contents of carbon (C), nitrogen (N), phosphorus (P), calcium (Ca), delta C-13, and delta N-15 in fishes were analyzed. Results illustrated that the ranges of elemental variations (C, N, P, and Ca) in the three fishes were 36.73 similar to 49.24%, 8.79 similar to 13.99%, 1.11 similar to 2.78%, and 1.16 similar to 4.58%, respectively while P content varied the most, resulting in variations in C:P and N:P in fishes. Correlation analysis determined the association among various parameters and illustrated that Ca content was significantly positively correlated with P content, which indicated that P content variation was attributed to the formation of fish bones and scales. The C, N, and P contents and their ratios were significantly correlated with body length and delta C-13 in the three fishes, indicating that the changes in C:N:P concentrations are due to individual development and food sources. Significant inter- and intraspecific differences in the body stoichiometry of the three fishes were found in this study, mainly due to differences in body size and diet. The aquatic organisms underwent individual development fluctuations in morphology and diet, which consequently altered their stoichiometric features.