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Cross-shelf transport, oxygen depletion, and nitrate release within a forming mesoscale eddy in the eastern Indian Ocean
Citation
Waite, AM and Beckley, LE and Guidi, L and Landrum, JP and Holliday, D and Montoya, J and Paterson, H and Feng, M and Thompson, PA and Raes, EJ, Cross-shelf transport, oxygen depletion, and nitrate release within a forming mesoscale eddy in the eastern Indian Ocean, Limnology and Oceanography, 61, (1) pp. 103-121. ISSN 0024-3590 (2016) [Refereed Article]
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Copyright Statement
Copyright 2015 The Authors. Licensed under Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) https://creativecommons.org/licenses/by-nc/4.0/
Abstract
Mesoscale eddies may drive a significant component of cross-shelf transport important in the ecology of shelf ecosystems and adjacent boundary currents. The Leeuwin Current in the eastern Indian Ocean becomes unstable in the austral autumn triggering the formation of eddies. We hypothesized that eddy formation represented the major driver of cross-shelf transport during the autumn. Acoustic Doppler Current Profiler profiles confirmed periodic offshore movement of ∼2 Sv of shelf waters into the forming eddy from the shelf, carrying a load of organic particles (>0.06 mm). The gap between inflow and outflow then closed, such that the eddy became isolated from further direct input of shelf waters. Drifter tracks supported an anticyclonic surface flow peaking at the eddy perimeter and decreasing in velocity at the eddy center. Oxygen and nutrient profiles suggested rapid remineralization of nitrate mid-depth in the isolated water mass as it rotated, with a total drawdown of oxygen of 3.6 mol m−2 to 350 m. Depletion of oxygen, and release of nitrate, occurred on the timescale of ∼1 week. We suggest that N supply and N turnover are rapid in this system, such that nitrate is acting primarily as a regenerated nutrient rather than as a source of new nitrogen. We hypothesize that sources of eddy particulate C and N could include particles sourced from coastal primary producers within ∼500 km such as macrophytes and seagrasses known to produce copious detritus, which is prone to resuspension and offshore transport.
Item Details
| Item Type: | Refereed Article |
|---|---|
| Keywords: | oxygen depletion, cross-shelf transport, nitrate release, mesoscale eddy, Indian Ocean |
| Research Division: | Earth Sciences |
| Research Group: | Oceanography |
| Research Field: | Physical oceanography |
| Objective Division: | Expanding Knowledge |
| Objective Group: | Expanding knowledge |
| Objective Field: | Expanding knowledge in the earth sciences |
| UTAS Author: | Thompson, PA (Dr Peter Thompson) |
| ID Code: | 118423 |
| Year Published: | 2016 |
| Web of Science® Times Cited: | 11 |
| Deposited By: | Directorate |
| Deposited On: | 2017-07-12 |
| Last Modified: | 2018-05-09 |
| Downloads: | 86 View Download Statistics |
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