Physiological consequences of parasite infection in the burrowing mud shrimp, Upogebia pugettensis, a widespread ecosystem engineer

The burrowing mud shrimp, Upogebia pugettensis, is an important ecosystem engineer throughout bays and estuaries along the Pacific coast of North America. Populations of U. pugettensis have recently declined throughout its range. A likely reason for this decline is the arrival of an invasive bopyrid isopod parasite, Orthione griffenis, which has colonised the system and increased in prevalence. We tested the following three hypotheses regarding this host–parasite system: (1) parasite infection is correlated with the volume of water processed by the host; (2) infection negatively affects host’s energetic state; and (3) infection causes feminisation in male hosts. We used several physiological and morphological measures to quantify the effects of this parasite infection on U. pugettensis. The parasite appears to have different physiological effects on male and female hosts. Our study provides mixed support for the previous theory that predicted the mechanistic interactions between this host and its new parasite. Recent examples from other systems have demonstrated that invasive parasites can have far-reaching influences when they infect ecosystem engineers. Given the negative effects ofO. griffenis onU. pugettensis, this invasive parasite may have similarly large impacts on Pacific Northwest estuaries throughout its invaded range. Additional keywords: host–parasite interactions, Orthione griffenis, Upogebia pugettensis, Yaquina Bay Oregon. Received 6 July 2011, accepted 24 September 2011, published online 8 November 2011