Thesis Title

The Effects of Suspended Sediment on the Attachment and Metamorphosis Success of Freshwater Mussel Parasitic Life Stages

Date of Graduation

Summer 2007


Master of Science in Biology



Committee Chair

M. Chris Barnhart


Unionoida, suspended sediment, glochidia, montmorillonite, gills

Subject Categories



Freshwater mussels (Unionoida) are of increasing concern to conservation biologists due to the large number of endangered species. The complex lifecycles of freshwater mussels begins as a temporary parasitic larval stage, the glochidium. Metamorphosis from larva to juvenile occurs during encapsulation on the gills of host fish. The portion of a mussel's lifecycle that represents the greatest bottleneck is attachment and encapsulation on the host. Suspended sediment is a potentially important factor affecting fish gill function and the successful attachment and metamorphosis of larval mussels. Young-of-the-year largemouth bass (Micropterus salmoides) were exposed to suspensions of montmorillonite clay (MC: 5, 2.5 or 1.25 g/L) or diatomaceous earth (DE: 2.5 or 1.25 g/L) for 72 or 96 hours. Treated fish and controls were infested with glochidia of fatmucket (Lampsilis siliquoidea). Sloughed glochidia and juveniles were recovered from each fish and quantified every other day post-infection. Microscopic examination showed that exposure to MC caused fusion of gill filaments and reduction of lamellae, particularly on distal portions. DE had less effect, despite the fact that DE is much more abrasive that MC. Exposure of fish to MC was associated with reduced glochidia attachment and reduced metamorphosis success. It appears that acute exposure of fish to suspended clay can affect their suitability as mussel hosts.


© Zachary S. Beussink