Master of Science (M.S.)
Moss Landing Marine Laboratories
I studied the variability in Ulva spp. in Elkhorn Slough, CA temporally and spatially. I measured changes in cover and biomass and combined them to determined changes in total abundance seasonally (every three months) from July 2003 to July 2004. Over this time period I found a significant seasonal difference in Ulva cover and a significant seasonal difference in Ulva biomass. There was also a significant interaction between season and section. Total abundance followed the same pattern of change as cover, suggesting Ulva mat cover was a better indicator of total abundance in Elkhorn Slough. To determine if seasonal changes were occurring at sub-seasonal time scales, the seasonal experiment was repeated at a smaller spatial scale from June 2004 to August 2004 with bi-weekly samples of cover and biomass. I found that seasonal variation in cover was significantly greater than sub-seasonal variation; however, seasonal and sub-seasonal biomass measurements were not significantly different. These results indicated that changes in cover were more gradual over time and biomass was highly variable at both time scales. I also investigated tides as a possible factor regulating Ulva mats in Elkhorn Slough. I found a localized phenomenon where increased Ulva mat movement was related to increased tidal range. Although the second sampling location did not show this same relationship, I hypothesize that tidal range plays an important role in the regulation of Ulva mats in Elkhorn Slough.
Schaadt, Timothy J., "Patterns and causes of variability in the cover, biomass, and total abundance of Ulva spp. in Elkhorn Slough, California" (2005). Capstone Projects and Theses. 89.