Presentation Title:
Evaluation of In Vitro-Cultured Mussels for the Restoration of Federally-Endangered Species of Toxolasma cyllindrellus in Tennessee, USA

Topic Area: 4f1. Restoration, Revitalization, Redevelopment, and Sustainability

Formatted Title:

Evaluation of In Vitro-Cultured Mussels for the Restoration of Federally-Endangered Species of Toxolasma cyllindrellus in Tennessee, USA

Background/Objectives:

Freshwater mussels play crucial roles in aquatic ecosystems; however, they are among the most endangered fauna in the United States. Thus, conserving and restoring these species is essential, particularly in biodiversity hotspots like the southeastern U.S. The pale lilliput (Toxolasma cyllindrellus) is an endangered freshwater mussel native to Tennessee and Alabama. This species was once believed to be extirpated from the Duck River system in Tennessee. However, it has since been rediscovered in Lick Creek, a tributary of the Duck River. Initially classified by the U.S. Fish and Wildlife Service as having low recovery potential, the restoration of large numbers of pale lilliput since 2014 led to its reclassification as having high recovery potential. This change has spurred efforts to downlist the species from its endangered status.

Freshwater mussels have a unique life cycle comprising three stages: glochidia (larvae), juvenile, and adult. During the larval stage, mussels rely on a fish host for nutrients, attaching to the fish during metamorphosis in a parasitic relationship. After metamorphosing into juveniles, they detach from the fish and live independently in the substrate as they mature into adults. Traditional propagation methods use fish hosts, but there is increasing interest in using in vitro culture techniques to replace the fish host during the glochidia stage. This method involves culturing glochidia in a nutrient medium within petri dishes and incubating as they transform into juveniles.

While traditional fish-host propagation has been effective for pale lilliput, it has limitations, including potential loss of glochidia and the need for extensive labor and space for fish collection and holding tanks. In vitro propagation offers a promising alternative by requiring less labor, providing a controlled environment, and potentially increasing juvenile mussel production. This approach offers significant benefits for the restoration of pale lilliput populations and other endangered freshwater mussels.

Approach/Activities:

This study aimed to assess differences in glycogen levels, a health biomarker, fatty acid profiles, and carbon and nitrogen stable isotopes (food web tracers and diet quality markers) between mussels cultured using fish hosts and those cultured in vitro. These results will provide insights into potential differences in mussel quality and health between the two propagation methods.

Results/Lessons Learned:

Preliminary results indicate no significant difference in glycogen levels or carbon and nitrogen stable isotope values between in vitro and fish-propagated pale lilliput individuals. Fatty acid profiles are still under analysis and will be included in the final presentation, along with release numbers. These findings suggest that in vitro culture could be a viable method for pale lilliput restoration, offering advantages in cost, space, and labor efficiency.

Andrew Hetrick

Affiliation

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Group 2, Poster Board #72: Restoration, Revitalization, Redevelopment, and Sustainability (Poster)