DNA Barcoding Permits Identification of Potential Fish Hosts of Unionid Freshwater Mussels

Fish have an ecologically significant role in the life-history of unionid freshwater mussels, as the larvae of most species are obligate ectoparasites (glochidia) on fish hosts. Although this ecological interaction is vital to freshwater mussel conservation, there is a paucity of data on fish-host specificity for many species. A species-specific DNA barcoding dataset utilizing the mitochondrial NADH dehydrogenase subunit 1 (ND1) gene was used to identify 154 glochidia attached to wild fish collected from March through August of 2013 in the Sabine and Neches rivers in Texas, U.S.A. These data include the first report of potential hosts for two state-threatened species, Fusconaia askewi (Marsh, 1896) and Pleurobema riddellii (I. Lea, 1862), as well as potential hosts for Amblema plicata (Say, 1817), Obliquaria reflexa (Rafinesque, 1820), Plectomerus dombeyanus (Valenciennes, 1827), Potamilus purpuratus (Lamarck, 1819), Quadrula mortoni (I. Lea, 1831), Q. verrucosa (Rafinesque, 1820), and Truncilla truncata (Rafinesque, 1820). Cyprinella lutrensis appears to be the primary host for F. askewi, as 50% (54/108) of its glochidia were found on this minnow species alone. Pleurobema riddellii may be a cyprinid specialist, infesting only C. lutrensis and Pimephales vigilax. Alternatively, F. askewi may be a host generalist, as glochidia were found encysted on 17 fish species suggesting that host fish availability may not be an important factor contributing to observed population declines. The findings here will be instrumental in the future conservation of these species, through the translocation to correct habitat and developing successful propagation programs