The role of sediment-induced light attenuation on primary production during Hurricane Gustav (2008)
<p>We introduced a sediment-induced light attenuation algorithm into a biogeochemical model of the Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) modeling system. A fully coupled ocean–atmospheric–sediment–biogeochemical simulation was carried out to assess the impact of sediment-in...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-10-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/17/5043/2020/bg-17-5043-2020.pdf |
| Summary: | <p>We introduced a sediment-induced light attenuation algorithm into a biogeochemical model of the Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) modeling system. A fully coupled ocean–atmospheric–sediment–biogeochemical simulation was carried out to assess the impact of
sediment-induced light attenuation on primary production in the northern Gulf of Mexico during the passage of Hurricane Gustav in 2008. When
compared with model results without sediment-induced light attenuation, our new model showed a better agreement with satellite data on both the
magnitude of nearshore chlorophyll concentration and the spatial distribution of offshore bloom. When Hurricane Gustav approached, resuspended sediment shifted the inner shelf ecosystem from a nutrient-limited one to a light-limited one. Only 1 week after Hurricane Gustav's landfall, accumulated nutrients and a favorable
optical environment induced a posthurricane algal bloom in the top 20 <span class="inline-formula">m</span> of the water column, while the productivity in the lower water column was still light-limited due to slow-settling sediment. Corresponding with the elevated offshore <span class="inline-formula">NO<sub>3</sub></span> flux
(38.71 mmol N m<span class="inline-formula"><sup>−1</sup></span> s<span class="inline-formula"><sup>−1</sup></span>) and decreased chlorophyll flux (43.10 mg m<span class="inline-formula"><sup>−1</sup></span> s<span class="inline-formula"><sup>−1</sup></span>), the outer shelf posthurricane bloom should have resulted from the cross-shelf nutrient supply instead of the lateral dispersed
chlorophyll. Sensitivity tests indicated that sediment light attenuation efficiency affected primary production when sediment concentration was
moderately high. Model uncertainties due to colored dissolved organic matter and parameterization of sediment-induced light attenuation are also discussed.</p> |
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| ISSN: | 1726-4170 1726-4189 |