Author: Grace K Roa,   (University of North Georgia, Oregon State University)

Designation: 

Description:
The native northeast Pacific intertidal blue mud shrimp, <em>Upogebia pugettensis</em>, is in steep decline range-wide due to intense infestations of the introduced Asian bopyrid isopod parasite, <em>Orthione griffenis</em>. The nonindigenous origins of the isopods in North America and the absence of refuges for mud shrimp preclude host resilience, equilibrium domains or otherwise long-term co-existence. Intervention by delaying or reversing the decline of mud shrimp will only be possible through understanding the ecology, energetics and population dynamics of this new host/parasite interaction, which has not been resolved for any marine bopyrid isopod in the world. Bopyrid isopod parasites effectively castrate their female hosts by hemolymph extraction, leading to total reproductive losses in female mud shrimp. Although host biomass can only be lost to isopods, mud shrimp weight per length does not decline with increasing parasite load. The energetics of this interaction, critical for understanding the population dynamics of this system, have therefore remained an enigma. We examined the energetics and population dynamics of this host/parasite interaction by analysis of the temporal variations in size frequencies of mud shrimp and their isopod parasites. We compared ages and growth rates of isopods among hosts to infer energetic losses and compared infested and uninfested host population size structures over time to estimate the effects of these energetic losses on host growth, reproduction and survival.

Category: Scientific Program Abstract > Special Sessions > CS30 Zooplankton ecology and physiology