Effects of relocation on metabolic profiles of freshwater mussels: Metabolomics as a tool for improving conservation techniques

1. Freshwater mussels are among the most endangered animals in North America. Although there are numerous state and federal programmes aimed at conserving them, knowledge of the effects of captivity and relocation remains limited. 2. Metabolomic techniques were used to assess the physiological state of freshwater mussels (Amblema plicata) relocated from the Muskingum River in Ohio to a conservation facility and to another stream in Ohio. Haemolymph samples were taken from mussels in the Muskingum River (MUS group), the facility (CAP group), and Big Darby Creek (DAR group) in September 2012 (month 3 post-relocation), November 2012 (month 5), May 2013 (month 11), and August 2013 (month 14). Samples were analyzed by gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry. 3. In total, 95 biochemicals were identified during the 2012 sampling period and 104 biochemicals during the 2013 sampling period. Glucose and lipid metabolism remained similar among all groups. Differences between the MUS group and the CAP and DAR groups were observed in altered amino acid and nucleotide metabolism. 4. The results are indicative of a general stress response, which is evident for a year post-relocation. Decreased levels of these metabolites are likely to be responsible for decreased growth rates and higher mortality often observed in relocated mussels.