Male seahorses and pipefishes of the family Syngnathidae have special structures for brooding embryos, including a placental-like structure called the brood pouch. Significant differences have been described in the brood pouch of two closely related pipefishes, Syngnathus floridae and Syngnathus fuscus. Specifically, the species differ in the contribution of proteins and lipids from the male and female parent to developing embryos. Developing S. fuscus rely more on nutrients provided by the male parent via the brood pouch, whereas S. floridae embryos depend more on nutrients supplied to the egg by the female parent. The goal of this research is to characterize the rate of nutrient transfer using stable isotopes and track the growth of brood pouch blood vessels by employing latex casts and scanning electron microscopy. Our studies are among the first to explore nutrient allocation and blood vessel patterns in the brood pouch in this diverse and interesting family. The results will help determine whether closely related species with similar brood pouch structures can have very different placental-like functions. In addition, this work will provide the foundation for future studies aimed at revealing the consequences of brood pouch morphology and function on species-specific sensitivities to environmental stresses such as hypoxia and water-borne contaminants. An extensive outreach project, focused on the novel mode of reproduction in pipefish and their habitat, will introduce the process of scientific discovery, further the understanding of estuarine systems and improve biological literacy for participating pre-college students.
