Parasites may be small, but their impact on coastal salt marshes is enormous. Dr. Ralph Appy examines the parasites of the longjaw mudsucker fish, showing how these organisms quietly influence the lives of their hosts, balance food webs, and reflect the effects of human activity. Drawing from extensive sampling in San Elijo Lagoon, this presentation illuminates the critical yet often overlooked role of vital parasites in preserving coastal wetland ecosystems.