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INTERTIDAL SEDIMENT TEMPERATURE VARIANCE AS A POSSIBLE LIMITING FACTOR FOR EELGRASSES ZOSTERA MARINA AND ZOSTERA JAPONICA IN YAQUINA BAY, OR
Citation:
Specht, D T. INTERTIDAL SEDIMENT TEMPERATURE VARIANCE AS A POSSIBLE LIMITING FACTOR FOR EELGRASSES ZOSTERA MARINA AND ZOSTERA JAPONICA IN YAQUINA BAY, OR. Presented at Estuarine Research Federation annual meeting, Seattle, WA, September 14-18, 2003.
Description:
The eelgrass species Zostera marina and Z. japonica co-occur in most Pacific Northwest estuaries; Z. marina is regarded as a native species, Z. japonica as non-indigenous, introduced in Yaquina Bay in approximately 1975. The mean tidal range is ~2 m, extreme ~3m. The vertical distribution (in this estuary) of the two species is quite different, Z. marina being restricted from ~2m below mean lower low water (MLLW) to ~1m above MLLW; Z. japonica is restricted to the upper ~1 m below mean higher high water (MHHW). Sediment temperature was measured on vertical transects from MLLW to MHHW at several sites by recording temperature sensors buried at 5 cm depth, at 15 minute intervals for periods up to 10 months. Analysis of continuous records covering ~3 years indicate that the daily root-rhizome zone sediment temperature cycle has significantly higher variance at or near MHHW than MLLW habitats; Z. marina habitat locations indicate relative intolerance to prolonged insolation and dessication and low-salinity immersion by rainfall during intertidal exposure; Z. japonica habitat locations indicate significantly higher tolerance these influences.