Falkenhayn, C. Washington State Dept. of Ecology, cfal451@ecy.wa.gov
Newton, J. Washington State Dept. of Ecology,
Clishe, C. Washington State Dept. of Ecology,
Moore, C. `. Washington State Dept. of Ecology,

 
PHYSICAL AND BIOLOGICAL PROCESSES IN A SHALLOW ESTUARY: CHARACTERIZING WILLAPA BAY, WA, BY HIGH-RESOLUTION SAMPLING
 
Estuaries are inherently dynamic areas of mixing between oceanic and river dominated systems. The understanding of these systems, thus, depends on assessing variation under the same timescales as are operative in the system. Willapa Bay, in SE Washington state is an estuary with two major rivers and one, fairly constricted, opening to the Pacific Ocean. We sought to determine the scales of variation of this system both in its physical and biological processes. With the use of moored sensors capable of 15-minute resolution, we were able to constrain the degree of variation due to tidal, seasonal and episodic differences and its variation along a N-S axis of the bay. In addition, monthly transects and primary productivity experiments help to define biological responses. The physical endmembers are primarily associated with proximity to oceanic (temperature, moderated by tides) and riverine (salinity, moderated by tides) influences. Light within the bay is a strong function of both season and sedimentary suspension, the latter of which is correlated with tidal velocity. The combination of light, stability and temperature lead to the spring bloom, which rapidly becomes nutrient-limited despite the shallow depths and proximity of the benthos to the pelagic water column. As the season progresses, nutrient limitation is weakest at the oceanward station implying that, even in this extremely well-mixed estuary, oceanic renewal of nutrients is greater than in situ nutrient regeneration.
 
Day: Friday, Feb. 5
Time: 09:15 - 09:30am
Location: Eldorado Hotel
 
Code: CS57FR0915E