Applying GIS to Santa Cruz Island: Density estimation of intertidal species clients.alexandria.ucsb.edu Carola Flores, Nic Galati, Jeff Overlock, and Heather Thakar Hucks

Research Background Specific Objectives Ecological spatial variation within the intertidal zone on Santa Cruz Island can be interpreted on different scales: Density of Species (number) Abundance of Species (diversity) Geographic Information Systems provide effective spatial tools for the analysis and visual representation of species density. Main Objective Develop a prototype GIS model to assist in the analysis of large quantities of data collected by PISCO and SWAT Specific Objectives Map intertidal species density within two ecological sites (Fraser and Valley) Evaluate potential intra-site spatial patterns of intertidal species density Evaluate potential inter-site density variation Look for potential causes and effects of the intertidal density variability

Valley Fraser

Datasets Santa Cruz Island DEM Sea-Surface Temperature Point Contact data Non-mobile intertidal species Classification table data Quadrat data Mobile intertidal species Classification table data Swath data Sea star presence or absence Santa Cruz Island DEM Sea-Surface Temperature

Data Sources Data Management Data provided in text files by Carol Blanchette, associated with the Coastal Biodiversity Surveys (CBS) on Santa Cruz Island, PISCO (UCSB), SWAT (UCSC) 30 meter DEM of Santa Cruz Island provided by Jeff Howarth Raster of Sea Surface Temperature provided by Bernardo Broitman Data Management Excel was used to open text files Deletion of data unnecessary for current analysis Latitude and Longitude coordinates converted to UTM for thousands of points Assignment of unique key for all points based on concatenation of X and Y locations Data converted into DBASE IV format DBF’s of Point Contact, Quadrat, and Swath Data for both Fraser and Valley sites, brought into ArcMap and converted into point shapefiles Shapefiles projected to the same coordinate system as the Santa Cruz Island DEM Species classification tables (in dbf format) brought into ArcMap and joined to shapefile attribute tables

Fraser Site 300 Swath Quadrat Point contact Valley Site 304 Swath Frasier Swath Quadrat Point contact

Problems with Data Data size: Large datasets from 10 years of intertidal surveying were difficult for data management Sampling: Datasets from only two ecological sites of Santa Cruz Island were used, thus results may not represent the density patterns of Santa Cruz’s intertidal species. Uncertainty: Datasets contain fine-scale multiple measurements. Due to the complex spatial distribution of species in the intertidal, to portray an accurate digital representation is challenging. Gremlins: We have very scientifically concluded that Excel is possessed. Odd occurrences in the excel files required hours of work to restore the files to a usable condition. http://home.hiwaay.net/~taylorc/toolbox/geography/geoutm.html

Intra-site Elevation DEM METHODS Intra-site Elevation DEM Created by Natural Neighbor Interpolation based on elevation data collected at each point contact location along the transects High Intertidal Zone Mid Intertidal Zone Low Intertidal Zone

Species Density Estimation Map Created for each data set within each site using Spatial Analyst Density Estimation METHODS

Intra-Site Species Density Created using Spatial Analyst Raster Calculator to combine the individual species density raster datasets, producing a single Intra-Site Species Density Map for each site METHODS

Intra-Site Species Density & Elevation, Fraser Meters RESULTS

Comparison of Non-Mobile Species & Elevation Meters ANALYSIS ANALYSIS

Comparison of Mobile Species & Elevation Meters ANALYSIS

Comparison of Starfish Density & Elevation Meters ANALYSIS

Comparison of Site Species Density & Elevation, Fraser Meters ANALYSIS

Intra-Site Species Density & Elevation, Valley Meters RESULTS

Comparison of Non-Mobile Species & Elevation Meters ANALYSIS

Comparison of Mobile Species & Elevation Meters ANALYSIS

Comparison of Starfish Density & Elevation Meters ANALYSIS

Comparison of Site Species Density & Elevation, Valley Meters ANALYSIS

Inter-site Comparison of Fraser & Valley Site Densities and Sea Surface Temperature ANALYSIS

Conclusions There are differences in density distribution of intertidal species between the two sampled sites. There is not a significant difference in the total count of intertidal species between the two sampled sites. Differences in density distribution of intertidal species between the two sampled sites could be a result of differences in intertidal topography: -An intertidal zone with relatively homogeneous surface elevation is more likely to exhibit an even density distribution of all species. - An intertidal zone with a less homogeneous surface elevation is more likely to exhibit a patchy density distribution of all species.

Conclusions Site 300 (Fraser) 304 (Valley) SST (°Celsius) 13 17 Non-Mobile Species 3030 2916 Mobile Species 128 178 Sea stars 24 122 Total Species 3182 3216 Our analysis does not indicate that Sea Surface Temperature had a measurable effect on the density distribution of intertidal species at Fraser site or Valley site in 2002. This unanticipated result may be attributed to: -the narrow temporal scope of our analysis (data set limited to 2002) -the narrow spatial scope of our analysis (data set limited to only two locations on Santa Cruz Island)

Applying GIS to Santa Cruz Island: Density estimation of intertidal species clients.alexandria.ucsb.edu Acknowledgements: Carol Blanchette, Josh Bader, Bernardo Broitman, Jeff Howarth