Seasonal variations in river discharge and nutrient export to a Northeastern Pacific estuary

Sigleo, Anne C.; Frick, Walter E.

doi:10.1016/j.ecss.2007.01.015

Cited by 57 publications

(44 citation statements)

References 22 publications

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“…During the wet season, riverine input is the largest source of DIN to the estuary, composing approximately 74% of the input, and 92% of the annual riverine N input is delivered during the wet season. Our estimates of riverine N loading are similar to previous published values (Quinn et al 1991;Sigleo and Frick 2007). Compton et al (2003) found that the presence of nitrogen fixing red alder (Alnus rubra) in PNW watersheds , and c chlorophyll a at Stations 5, 7, 8, 9, and conditions near the entrance (Station 1) during May-September 2002 influences the N export from the watershed into streams.…”

Section: Watershed Inputssupporting

confidence: 81%

“…The largest source of error in the estimate of riverine loading is the limited number of nutrient samples used to generate the relationship between flow and nutrient levels; however, our estimates of riverine nutrient loading are similar to the estimate of Sigleo and Frick (2007) based on recent data with higher sample size at Chitwood and Elk City. The two largest sources of error in the estimates of oceanic loading for the dry season are that one value was used to represent the DIN for the entire flood tide and not all flood tides were sampled.…”

Section: Sources Of Uncertainty In Nitrogen Loading Estimatescontrasting

confidence: 43%

“…This estimation of the ungaged portions of the watershed is only valid if the freshwater inflow per unit area of the gauged portion of the watershed is the same as for the ungauged portion and the DIN levels in the two tributaries are similar. Previous studies have shown that the DIN levels in Elk Creek and the Yaquina River are approximately equal (Sigleo and Frick 2007). In addition, limited streamflow measurements at Elk City indicate that flow at Elk City is about 2.2 times that at Chitwood (n=39).…”

Section: Discussionmentioning

confidence: 96%

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Coupling Between the Coastal Ocean and Yaquina Bay, Oregon: Importance of Oceanic Inputs Relative to Other Nitrogen Sources

Brown

Ozretich

2009

Estuaries and Coasts

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Section: Watershed Inputssupporting

confidence: 81%

Section: Sources Of Uncertainty In Nitrogen Loading Estimatescontrasting

confidence: 43%

Section: Discussionmentioning

confidence: 96%

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Coupling Between the Coastal Ocean and Yaquina Bay, Oregon: Importance of Oceanic Inputs Relative to Other Nitrogen Sources

Brown

Ozretich

2009

Estuaries and Coasts

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“…1), when discharge from these Coast Range rivers is over an order of magnitude higher than in the summer (e.g., Colbert and McManus 2003;Sigleo and Frick 2003). Wintertime discharge centers on episodic storm events that occur at a frequency of 1-3 per month from November through April (Colbert and McManus 2003;M.…”

mentioning

confidence: 99%

Riverine input of macronutrients, iron, and organic matter to the coastal ocean off Oregon, U.S.A., during the winter

et al. 2006

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Three cross-shelf transects were conducted off northern Oregon in February, 2003, coincident with flooding of Coast Range rivers, to assess the riverine impact on coastal ocean biogeochemistry. During downwelling conditions, low salinity river-influenced water was located in a narrow band near the coast and contained elevated macronutrient, iron, and organic carbon concentrations. Wind relaxation allowed the river-influenced water to spread out at the surface across the shelf. Nutrients supplied by the rivers could result in winter carbon fixation equating to ,20% of the summer upwelling carbon fixation if conditions are suitable for phytoplankton growth, which is likely on the basis of recent studies. This implies that wintertime production may be significant and requires further study. Iron supplied by the rivers is sufficient to support the entire summer upwelling production and because downwelling conditions prevail during the winter and minimize cross-shelf transport, this iron may be retained on the shelf to support the summer phytoplankton blooms. Of the major eastern boundary current systems, the northern California Current (including Oregon) and Portugal Current (i.e., Iberian Peninsula) have the highest riverine discharge rates normalized to coastline length. In contrast, riverine inputs to the central California, Canary (i.e., northwest Africa), Benguela and Peruvian Current systems averaged only 3-35% of that in Oregon. This patchy riverine input (and narrower shelves) might explain why iron limitation is more widespread off California and Peru than Oregon. These results show that small coastal rivers, characteristic of the U.S. Pacific Northwest, can significantly alter coastal biogeochemical cycles and influence ecosystem structure.The coastal ocean plays a key role in global biogeochemical cycles and marine food webs. In recent years, advances have been made in linking atmospheric and physical dynamics to ecosystem structure and function during the productive summer season in eastern boundary current systems. Unfortunately, that progress has not been matched by increased study or enhanced understanding of wintertime conditions. In fact, relatively little is known about wintertime biogeochemical or food web conditions in these types of systems.Results from modeling and field observations show that the wintertime physical dynamics of eastern boundary current systems are quite different than during the summer upwelling season. Off Oregon for example, mean wintertime coastal wind direction is to the north and strong north/northeastward propagating storms frequently occur (Halliwell and Allen 1987;Strub et al. 1987). Northward winds cause onshore Ekman transport of surface waters, leading to development of a downwelling front at the 100-150-m isobath (Allen and Newberger 1996; Austin and Barth 2002). In the region of the front, the water column can be vertically homogenous (Barth et al. unpubl.). Currents inshore of the front are predominately to the north, and cross-shelf circulation is believ...

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“…3). The average wintertime discharge from the Oregon Coast Range rivers is estimated to be ∼ 2570 m 3 s −1 (Wetz et al, 2006), which is more than an order of magnitude higher than that in the summer (Colbert and McManus, 2003;Sigleo and Frick, 2003). However, the CR discharge in May to June 2007 reached its maximum of ∼ 15 000 m 3 s −1 (Evans et al, 2013), which should be approximately 2 orders of magnitude higher than the discharge of small rivers.…”

Section: Dic and No 3 In The Upper Waters Off Oregon And Northern Calmentioning

confidence: 94%

Diagnosing CO<sub>2</sub> fluxes in the upwelling system off the Oregon–California coast

et al. 2014

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Abstract.It is generally known that the interplay between the carbon and nutrients supplied from subsurface waters via biological metabolism determines the CO 2 fluxes in upwelling systems. However, quantificational assessment of such interplay is difficult because of the dynamic nature of both upwelling circulation and the associated biogeochemistry. We recently proposed a new framework, the Oceandominated Margin (OceMar), for semi-quantitatively diagnosing the CO 2 source/sink nature of an ocean margin over a given period of time, highlighting that the relative consumption between carbon and nutrients determines if carbon is in excess (i.e., CO 2 source) or in deficit (i.e., CO 2 sink) in the upper waters of ocean margins relative to their off-site inputs from the adjacent open ocean. In the present study, such a diagnostic approach based upon both couplings of physics-biogeochemistry and carbon-nutrients was applied to resolve the CO 2 fluxes in the well-known upwelling system off Oregon and northern California of the US west coast, using data collected along three cross-shelf transects from the inner shelf to the open basin in spring/early summer 2007. Through examining the biological consumption on top of the water mass mixing revealed by the total alkalinity-salinity relationship, we successfully predicted and semi-analytically resolved the CO 2 fluxes showing strong uptake from the atmosphere beyond the nearshore regions. This CO 2 sink nature primarily resulted from the higher utilization of nutrients relative to dissolved inorganic carbon (DIC) based on their concurrent inputs from the depth. On the other hand, the biological responses to intensified upwelling were minor in nearshore waters off the Oregon-California coast, where significant CO 2 outgassing was observed during the sampling period and resolving CO 2 fluxes could be simplified without considering DIC/nutrient consumption, i.e., decoupling between upwelling and biological consumption. We reasoned that coupling physics and biogeochemistry in the OceMar model would assume a steady state with balanced DIC and nutrients via both physical transport and biological alterations in comparable timescales.

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Seasonal variations in river discharge and nutrient export to a Northeastern Pacific estuary

Cited by 57 publications

References 22 publications

Coupling Between the Coastal Ocean and Yaquina Bay, Oregon: Importance of Oceanic Inputs Relative to Other Nitrogen Sources

Coupling Between the Coastal Ocean and Yaquina Bay, Oregon: Importance of Oceanic Inputs Relative to Other Nitrogen Sources

Riverine input of macronutrients, iron, and organic matter to the coastal ocean off Oregon, U.S.A., during the winter

Diagnosing CO<sub>2</sub> fluxes in the upwelling system off the Oregon–California coast

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Seasonal variations in river discharge and nutrient export to a Northeastern Pacific estuary

Cited by 57 publications

References 22 publications

Coupling Between the Coastal Ocean and Yaquina Bay, Oregon: Importance of Oceanic Inputs Relative to Other Nitrogen Sources

Coupling Between the Coastal Ocean and Yaquina Bay, Oregon: Importance of Oceanic Inputs Relative to Other Nitrogen Sources

Riverine input of macronutrients, iron, and organic matter to the coastal ocean off Oregon, U.S.A., during the winter

Diagnosing CO&lt;sub&gt;2&lt;/sub&gt; fluxes in the upwelling system off the Oregon–California coast

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Product

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Diagnosing CO<sub>2</sub> fluxes in the upwelling system off the Oregon–California coast