similar, 14 and 13 g/m 2 , respectively. Biomass of these species was similar in Oregon 
and Washington. Mean biomass of green algae was similar in California (mean = 26 
g/m 2 ) and Oregon (mean = 30 g/m 2 ) and somewhat lower in Washington (mean = 9 
g/m 2 ). As algae were only classified into large taxonomic groups, it is difficult to explain 
geographic differences in biomass. 
Transect Species Assemblages and Percent Cover 
Vegetation was present along the transects at 171 sites of the 217 sites sampled. 
Vegetation recorded on transects included 31 emergent macrophytes, including three 
nonindigenous species (C. coronopifolia, L. latifolium, and S. alterniflora), two 
seagrasses (Z. marina and Z. japonica), and algal taxa (Appendix Table 4). 
Seagrasses were found at 25 and 28 sites, respectively. Three groups of macroalgae, 
green algae, brown algae and red algae, were identified in the transects. Green algae 
(e.g., Ulva, Cladophora, Enteromorpha) were observed at 84 sites. Red algae were 
observed in one transect and brown algae in four transects. 
Throughout the West, the vegetation quadrats were dominated by bare area 
(Figure 3.3.15). Relative bare area ranged between 4 and 100% throughout the West 
(Figure 3.3.15). Mean relative cover of emergent macrophytes (21%) and macroalgae 
(20%) were similar and higher than that of seagrass (9%) throughout the West (Figure 
3.3.15). The relative cover of emergent macrophytes ranged between 1 and 100% in 
the West (including all San Francisco Bay sites) (Appendix Table 8). Most emergent 
macrophyte taxa occurred in the transects of only a few sites (Appendix Table 4), with 
84% of taxa occurring at three or fewer sites. The most frequently occurring emergent 
macrophyte taxa were S. virginica, J. carnosa, D. spicata and Spartina foliosa. Similar 
to the vegetation quadrats, the low emergent vegetation cover at most sites may be 
attributed to the fact that most of the sites in the sample frame were classified as 
unvegetated tide flats (Figure 3.1.2). 
Percentage of bare area in the transects was higher for sites in Oregon and 
Washington than those in California (Figure 3.3.15). Mean percentage of bare area was 
59% in Oregon and 60% in Washington. Mean bare area was 38% in California and 
36% for sites in San Francisco Bay. The relative cover by major plant groups 
(emergent macrophytes, seagrass, algae) displayed geographic patterns. Relative 
abundance of emergent macrophytes was lower in Washington (mean = 3%) and 
Oregon (mean = 9%) than for sites in California (mean = 43%) and San Francisco Bay 
(mean = 78%). Relative cover of seagrass was higher than that of emergent 
macrophytes at Washington sites (Figure 3.3.15). Cover of emergent macrophytes was 
higher than that of algae or seagrass in California and San Francisco Bay sites. Mean 
relative cover of seagrass was 0% in California and San Francisco Bay sites. Mean 
relative cover of algae (all types) was higher than that of emergent macrophytes and 
seagrass in Oregon sites (Figure 3.3.15). Mean relative cover of algae (all types) was 
highest for Oregon sites. Cover of emergent macrophytes was higher than that of algae 
or seagrass in California and San Francisco Bay sites. Similar to vegetation quadrats, 
46 
