Quantifying cross-shelf and vertical nutrient flux in the Coastal Gulf of Alaska with a spatially nested,coupled biophysical model |
| |
| Institution: | 1. Joint Institute for the Study of the Atmosphere and Ocean, University of Washington, P.O. Box 357941, Seattle, WA 98195, USA;2. Alaska Fisheries Science Center, 7600 Sand Point Way N.E., Seattle, WA 98115, USA;3. Institute of Marine and Coastal Sciences, Rutgers University, 71 Dudley Road, New Brunswick, NJ 08901-8521, USA;4. Pacific Marine Environmental Laboratory, 7600 Sand Point Way N.E., Seattle, WA 98115, USA;1. College of Ocean and Atmospheric Sciences,Oregon State University, 104 COAS Admin Bldg, Corvallis, OR 97331-5503 USA;2. Joint Institute for the Study of the Atmosphere and Ocean, University of Washington, Box 354925, Seattle, WA 98195 USA;1. CSIRO Oceans and Atmosphere, Indian Ocean Marine Research Centre, M097 64 Fairway, Crawley, Western Australia 6009, Australia;2. University of Western Australia, Oceans Institute, Indian Ocean Marine Research Centre, M470 35 Stirling Highway, Crawley, Western Australia 6009, Australia;3. BMT Western Australia, 4/20 Parkland Rd, Osborne Park, Western Australia 6017, Australia;4. Department of Education WA, 151 Royal Street, East Perth, Western Australia 6004, Australia;5. CSIRO Oceans and Atmosphere, GPO Box 1600, Canberra, Australian Capital Territory 2601, Australia;6. CSIRO Oceans and Atmosphere, PO Box 1538, Hobart, Tasmania 7001, Australia;1. University of Maryland Center for Environmental Science, Horn Point Laboratory, P.O. Box 775, Cambridge, MD 21613, USA;2. 10 Marine Biology, Department of Marine Biology and Paleoenvironment, Lamont Doherty Earth Observatory at Columbia University, 61 Route 92, Palisades, NY 10964, USA |
| |
| Abstract: | The Coastal Gulf of Alaska (CGOA) is productive, with large populations of fish, seabirds, and marine mammals; yet it is subject to downwelling-favorable coastal winds. Downwelling regions in other parts of the world are typically much less productive than their upwelling counterparts. Alternate sources of nutrients to feed primary production in the topographically complex CGOA are poorly known and difficult to quantify. Here we diagnose the output from a spatially nested, coupled hydrodynamic and lower trophic level model of the CGOA, to quantify both horizontal and vertical nutrient fluxes into the euphotic zone. Our nested model includes both nitrogen and iron limitation of phytoplankton production, and is driven by a fine-scale atmospheric model that resolves the effects of local orography on the coastal winds. Results indicate significant “rivers” of cross-shelf nitrogen flux due to horizontal advection, as well as “fountains” of vertical transport over shallow banks due to tidal mixing. Using these results, we constructed a provisional budget of nutrient transport among subregions of the CGOA. Contrary to expectations, this budget reveals substantial upwelling of nutrients over major portions of the shelf, driven by local wind-stress curl. These effects are large enough to overwhelm the smaller downwelling flux at the coast throughout the growing season. Vertical mixing by winds and tides, and horizontal flux from the deep basin, are other substantial contributors to nutrients above the 15-m horizon. These findings help to explain the productivity of this coastal ecosystem. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
