Limited Shifts in Sulfur Stable Isotopes in Response to Hypoxia Exposure of Atlantic Croaker, Micropogonias undulatus
摘要
Bottom water hypoxia can affect coastal communities by altering trophic interactions of consumers and prey depending on their low oxygen tolerances. Consumer tissue stable isotopes can potentially be used to assess shifts in foraging behavior between distinct production sources in response to hypoxia exposure. This study investigated the ability of δ34S stable isotope values to detect responses of Atlantic Croaker, Micropogonias undulatus, to hypoxia in the northern Gulf of Mexico. Values of δ34S in hypoxic exposed fish, as identified by their otolith chemistry compositions, were significantly lower than normoxic fish in one of the two collection years. When comparing δ34S values to previously analyzed δ13C values from the same fish, bivariate isotope niche areas of hypoxic fish were 28% smaller and 580% larger than normoxic fish, depending on the collection year. In addition, δ34S values of the hypoxic fish were negatively correlated with hypoxia index values from their otoliths, but these two metrics were not correlated in normoxic fish. These results collectively illustrated the complex responses for consumer δ34S values and limited systematic shifts of this isotopic indicator in response to hypoxic stress.