Effect of Diet and Low Dissolved Oxygen on Some Life History Parameters of Acartia Tonsa (Copepoda

Many productive coastal areas, such as estuaries, are important fisheries. However, increased respiration associated with the high productivity often occurring in coastal zones may result in low dissolved oxygen conditions (dysoxia). The areal magnitude of coastal waters with low dissolved oxygen is expected to increase in the future. Therefore, understanding how organisms are affected by dysoxia is important for predicting changes to fisheries. This research extends the current knowledge of how pelagic organisms are affected by sublethal and lethal dissolved oxygen concentrations under different diet conditions. The warm-water copepod, Acartia tonsa, was chosen as the model organism due to its abundance in many temperate and tropical coastal areas. Results suggest that A. tonsa egg production may not be significantly decreased by dysoxia under some conditions of food limitation. Temperature and the timing of food availability when oxygen is present affected egg production in A. tonsa exposed to fluctuating food and dissolved oxygen. Food quality also significantly affected egg production of A. tonsa under low oxygen, but no significant differences in egg production efficiencies were found between a high- or low-carbohydrate diet. Egg production was higher and development time shorter under dysoxia for A. tonsa populations from environments with seasonal severe dysoxia compared to A. tonsa from an environment with less severe dysoxia. Therefore, the consequences of low oxygen stress on Acartia tonsa population dynamics may be affected by migration behavior, food quantity, food quality, temperature, the intensity and frequency of low dissolved oxygen waters, and the history of dysoxia.