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- Title
Simulating the effects of phosphorus limitation in the Mississippi and Atchafalaya River plumes.
- Authors
Laurent, A.; Fennel, K.; Hu, J.; Hetland, R.
- Abstract
The continental shelf of the northern Gulf of Mexico receives high dissolved inorganic nitrogen and phosphorus loads from the Mississippi and Atchafalaya rivers. The nutrient load results in high primary production in the river plumes and contributes to the development of hypoxia on the Texas-Louisiana shelf in summer. While phytoplankton growth is considered to be typically nitrogen-limited, phosphorus limitation has been observed in this region during periods of peak river discharge in spring and early summer. Here we investigate the presence, spatio-temporal distribution and implications of phosphorus limitation in the plume region using a circulation model of the northern Gulf of Mexico coupled to a multi-nutrient ecosystem model. Results from a 7-yr simulation (2001-2007) compare well with available observations and suggest that phosphorus limitation develops every year between the Mississippi and Atchafalaya deltas. Model simulations show that phosphorus limitation results in a delay and westward shift of a fraction of river-stimulated primary production. The consequence is a reduced flux of particulate organic matter to the sediment near the Mississippi delta, but enhanced fluxes westward in the Atchafalaya and far-field regions. Two discharge scenarios with altered river phosphate concentrations (±50 %) reveal a significant variation (±40% in July) in the spatial extent of phosphorus limitation with changes in phosphate load.
- Subjects
MISSISSIPPI River; ATCHAFALAYA River (La.); LOUISIANA; PHOSPHORUS in water; SIMULATION methods &; models; PLUMES (Fluid dynamics)
- Publication
Biogeosciences Discussions, 2012, Vol 9, Issue 5, p5625
- ISSN
1810-6277
- Publication type
Article
- DOI
10.5194/bgd-9-5625-2012