Epizoans and Predation Traces of Devonian Hay River Formation Brachiopods: Indicators of Complex Ecosystems and Ties to the Iowa Basin

Two brachiopod communities from the Devonian Hay River Formation units B and C are moderately to heavily encrusted by epizoans. The unit B community bears evidence of predatory attacks. This community was much more diverse in terms of host brachiopods and attached epizoans; furthermore, epizoans were highly abundant. Predation traces occurred only on brachiopod species that were heavily encrusted. The unit C community is much less diverse in encrusters and epizoans, and brachiopods were smaller on average. In this community, low epizoan abundance may have arisen from influences of nearby biostromes or from brachiopod size effects. Using Bray-Curtis polar ordination, we compared epizoan and brachiopod diversity to those from four stratigraphic units and nine localities from Iowa and Ohio, USA. Our results suggest that Hay River epizoan assemblages are most similar to those from Iowa, regardless of age, and support interbasin exchange patterns recovered from studies of brachiopod migration.