Annelid-myxosporean interactions

Abstract

This chapter provides an overview of the diversity of annelids parasitized by myxosporeans in both marine and freshwater systems and reviews the interactions between myxosporeans and their annelid hosts during the socalled actinospore phase of the myxosporean life cycle. Both host and environmental factors can influence infection. Our chapter examines these influences from the initial infection of annelids through to the release of spores infectious to fish. Topics covered include how myxosoporean infections may relate to the trophic ecology of annelid hosts and what factors may influence dispersal and increase encounter rates of infectious spores with hosts. We also review the little that is known about annelidmyxosporean interactions, focusing on patterns of host specificity, host susceptibility and host immune defenses. Finally, we examine development within and effects on annelid hosts. To illustrate these interactions we draw primarily on examples from the relatively well-studied freshwater salmon parasites Myxobolus cerebralis and Ceratonova shasta, and interactions with their respective annelid hosts.