11.5 Epiphyte Patterns and Impact on Z. marina 
The Chesapeake Bay water quality criteria for shallow water bay grass includes values for 
percent of ambient light reaching a plant through the water column, and a value for percent of light at 
the leaf, after attenuation by epiphytes. A study of epiphytes growing on Z. marina leaves was 
conducted within the Yaquina Estuary from 2000 though 2004 at six stations distributed between 3.5 
and 17 km upriver from the mouth of the Yaquina Estuary. Methodological details are presented in 
Appendix B. 
11.5.1 Spatial and Temporal Patterns in Epiphytes 
In the Yaquina Estuary, there was a general annual pattern in 2000 though 2003 in which 
epiphyte biomass increased in the spring to a maximum in the summer and fall. This statistically 
significant parabolic relationship was most clearly seen on the older, external seagrass blades within a 
shoot (Figure 11.8). For unknown reasons, this yearly pattern was not observed in the 2004 samples. 
In the Yaquina Estuary, epiphyte biomass per unit surface area of seagrass leaves was higher in 
Zone 1 (ocean dominated) than in Zone 2 (river dominated) in both wet and dry seasons (Figure 11.9). 
However, only the dry season differences were statistically significant. Epiphyte biomass per unit leaf 
surface area was higher in the dry season than the wet season within both zones (Lee et al., 2006). 
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