Date of Graduation

Spring 2020


Master of Science in Biology



Committee Chair

M. Chris Barnhart


The native freshwater mussels, Order Unionida, have suffered many species extinctions and loss of abundance. Two important threats to native mussels are loss of habitat and loss of access to the vertebrate hosts of the parasitic mussel larvae. The Salamander mussel, Simpsonaias ambigua, is a habitat specialist, living under flat rocks. It is often found in direct association with its only known host, the common mudpuppy, Necturus maculosus. This association could result from movement and habitat selection by the mussels themselves. Alternatively, it might result from the deposition of juveniles by a resident host. Habitat selection and host detection by Simpsonaias was examined using choice arenas and choice flumes. Variables tested in arenas included taxis with respect to flow, toward vertical edges, to positions beneath clear or opaque shelters, and aggregation with other individuals. Variables tested in choice flumes included movement toward host scent and dissolved oxygen. Significantly more Simpsonaias were found upstream, underneath shelters, underneath dark shelters, in contact with one another, and along the edge of the arena respectively. In choice flumes, mussels showed no preference for host salamander scented water, fish scented water, or control well water. Mussels showed no taxis with respect to dissolved oxygen at 15C, while at 20C mussels were found more often on the hypoxic side, perhaps because of inhibition of locomotion by hypoxia. Overall, the results show that Simpsonaias prefer and actively seek darkened shelter where they come into contact with solid surfaces and with each other. The results also suggest that construction of suitable shelters could be a useful conservation tool for this species.


Simpsonaias ambigua, Necturus maculosus, habitat, scent cues, hypoxia, conservation

Subject Categories

Behavior and Ethology | Biology | Terrestrial and Aquatic Ecology


© Eric A. Stegmann

Open Access