Senior Theses 2008
Courtney Nosach (2008) Environmental Effects on the Germination of the South Florida Submerged Macrophyte Vallisneria americana (wild celery)
Faculty Advisor: Jeannine Lessmann
This study examined the effect of the environmental conditions of temperature, salinity and light experimentally on the germination of seeds from a south Florida seagrass population of Vallisneria americana (wild celery). Experiments were conducted within a growth chamber using a randomized block split-plot design; the main plot was temperature (30, 24, 18°C) with subplots of salinity (0, 5, 10, 15 psu) and light (presence, absence). There was a statistically significant difference (p<0.001) among temperature treatments with more seeds germinating (final percent germinated) in higher (30°C) rather than lower temperatures regardless of either salinity and/or light levels. There was a statistically significant three-way interaction (p<0.001) among the temperature, salinity and light treatments on germination rate. Germination rate was directly related to temperature and light, and inversely related to salinity. Overall, germination rate was fastest in the 30°C, 0 psu, light present treatment and slowest in the 18°C, 15 psu, light treatment. Also, time to last germination significantly increased as temperature increased (p<0.001). Comparatively, neither the main effects nor their interactions displayed a statistically significant effect on time to first germination. In general, these experiments suggest that V. americana seed germination will be maximized when the ambient water is at a temperature of 30°C, a salinity of <5 psu, and in the presence of light. Therefore the recovery and long term management of V. americana within the Caloosahatchee River is dependent upon the ability of managers to maintain conditions at levels amenable to maximize seed germination.