Background/Question/Methods Planktonic eggs are concentrated sources of essential fatty acids, and super-abundances of eggs are released in spatiotemporally discrete patches, called egg boons. These represent pulsed nutritional resources for egg consumers. While a variety of marine animals consume eggs, the role of egg boons in energy transfer through food webs has received little attention. This ongoing study tests three hypotheses: egg boons provide a pathway through which essential fatty acids (EFAs) are redistributed counter to the main direction of trophic flow; stores of EFAs in egg consumers increase during egg boons and remain elevated after the spawning season; and egg boons are beneficial to the condition of egg consumers. Our research exploits an annual egg boon produced by a spawning aggregation of red drum (Sciaenops ocellatus) near Port Aransas, Texas. In a combination of field sampling and laboratory experiments, we measure fatty acids, lipid content, and bulk stable isotopes to define trophic links between the egg boon and a selection of lower-trophic-level taxa. We simulate egg boons in laboratory feeding experiments to enhance interpretation of data from field sample by comparing egg consumers with non-consumers. We assess changes in condition attributed to egg consumption in target taxa using a nucleic acid biomarker (RNA:DNA). Results/Conclusions Preliminary results from feeding experiments indicate that measurable turnover of fatty acid pools in the egg consumers (Chrysaora and Pleurobrachia) occurred within 2-4 weeks, where consumer fatty acid composition changed from the “wild” state toward the profile of their diet (Artemia or Artemia plus red drum eggs). Results also indicate that certain combinations of fatty acids could potentially be used as egg biomarkers to trace egg consumption in consumers. Furthermore, both red drum eggs and adult red drum have similar high δ15N stable isotope values, indicative of large piscivorous fishes, suggesting that δ15N could be used as a marker of egg consumption by lower trophic levels. This research examines how egg consumption redistributes EFAs within food webs, and provides a context for considering potential controls and trophic bottlenecks that cannot be explained from the traditional element-limitation perspective. Further, if egg boons are an important nutritional subsidy to select groups of consumers, egg boons and their variations may have important impacts on secondary production in marine food webs. This could happen when fish populations are heavily exploited during spawning aggregations, possibly altering nutrient flow of the system.
