Thursday, August 7, 2008

PS 67-141: Reintroduction of an endangered riverine plant through artificial seed packets - CANCELLED

Mara L. Alexander, U.S. Fish and Wildlife Service

Background/Question/Methods

Zizania texana is a federally-listed endangered species that grows only in the San Marcos River, San Marcos, Hay County, Texas, USA. Environmental stresses, human interference and intrusion by invasives may have contributed to the decline and limited distribution of Z. texana. Zizania texana tends to occupy areas with moderately coarse to coarse sandy substrates. This species is predominantly found in shallow areas at depths of less than 1 m and velocities greater than 0.46 m/s. The current restoration method of transplanting and anchoring small Z. texana plants in high flow areas has had limited success, as they are often lost due to high flow, substrate shifting, and possible human interference. It might be advantageous for the continued success of the species to devise a restoration method whereby seeds can be planted and allowed to securely anchor themselves via their own root structures to maintain stability without compromising growth rates and viability. Because this plant is in such small quantities, the number of seeds available to use for restoration is small. Restoring a section of river using packets of seeds placed in optimal Z. texana habitat may make the most efficient use of the limited seed bank. I created artificial seed-packets using materials such as surgical gauze, coffee filters and onion bags (a fine mesh bag commonly used to hold onions/potatoes) to first establish if Z. texana seeds can germinate through these materials under laboratory conditions and then to determine if these materials will hold up to the flowing water in the San Marcos River. 

Results/Conclusions There were significant differences in germination success (p < 0.005) and ability to withstand river flows between the three materials (p < 0.05). I also examined the percentage of new Z. texana plants that persisted in the river after a 2-, 4-, 6-, and 12-week period per seed-packet material.