Physical and Biological Processes at the Middle Atlantic Bight Shelf-Break Front
The Middle Atlantic Bight (MAB) is a highly productive ecosystem, supporting several economically important commercial fisheries. Chlorophyll enhancement at the MAB shelf-break front has been observed only intermittently, despite numerous studies that suggest persistent upwelling at the front. High...
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| Format: | Thesis |
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Massachusetts Institute of Technology
2023
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| Online Access: | https://hdl.handle.net/1721.1/150558 |
| _version_ | 1811073249745829888 |
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| author | Hirzel, Andrew Joseph |
| author2 | McGillicuddy, Jr., Dr. Dennis J. |
| author_facet | McGillicuddy, Jr., Dr. Dennis J. Hirzel, Andrew Joseph |
| author_sort | Hirzel, Andrew Joseph |
| collection | MIT |
| description | The Middle Atlantic Bight (MAB) is a highly productive ecosystem, supporting several economically important commercial fisheries. Chlorophyll enhancement at the MAB shelf-break front has been observed only intermittently, despite numerous studies that suggest persistent upwelling at the front. High resolution cross-frontal transect crossings were collected from three two-week cruises in April 2018, May 2019, and July 2019. Chapter 2 focused on applying a novel method of classifying planktonic images taken by a Video Plankton Recorder to enable processing of the large volumes of data collected with the instrument. Chapter 3 investigated cross-frontal trends by temporally averaging in both Eulerian and frontally-aligned coordinates. For April 2018, transient chlorophyll enhancement was seen at the front in individual transects and within the frontally-aligned mean transect, but not within the Eulerian mean transect. The Eulerian mean for May 2019 showed chlorophyll enhancement as a result of frontal eddies, which were further explored in chapter 4. No frontal enhancement was observed in July 2019. The frontal eddies observed in May 2019 were simulated using an idealized model, which showed that upwelling occurred within both of the frontal eddies, despite having opposite rotational directions. This result was consistent with nutrient enhancement observed within the centers of both eddies. Biological enhancement within each eddy was observed, which may have been a result of advection from source waters and/or a local response to upwelled nutrients. The influence of frontal variability and frontal eddies on nutrients and plankton at the front argues for the necessity for 3-D models to fully explain frontal behavior and its effects on biological responses. |
| first_indexed | 2024-09-23T09:30:33Z |
| format | Thesis |
| id | mit-1721.1/150558 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T09:30:33Z |
| publishDate | 2023 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/1505582023-04-26T03:44:30Z Physical and Biological Processes at the Middle Atlantic Bight Shelf-Break Front Hirzel, Andrew Joseph McGillicuddy, Jr., Dr. Dennis J. Joint Program in Biological Oceanography. Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences The Middle Atlantic Bight (MAB) is a highly productive ecosystem, supporting several economically important commercial fisheries. Chlorophyll enhancement at the MAB shelf-break front has been observed only intermittently, despite numerous studies that suggest persistent upwelling at the front. High resolution cross-frontal transect crossings were collected from three two-week cruises in April 2018, May 2019, and July 2019. Chapter 2 focused on applying a novel method of classifying planktonic images taken by a Video Plankton Recorder to enable processing of the large volumes of data collected with the instrument. Chapter 3 investigated cross-frontal trends by temporally averaging in both Eulerian and frontally-aligned coordinates. For April 2018, transient chlorophyll enhancement was seen at the front in individual transects and within the frontally-aligned mean transect, but not within the Eulerian mean transect. The Eulerian mean for May 2019 showed chlorophyll enhancement as a result of frontal eddies, which were further explored in chapter 4. No frontal enhancement was observed in July 2019. The frontal eddies observed in May 2019 were simulated using an idealized model, which showed that upwelling occurred within both of the frontal eddies, despite having opposite rotational directions. This result was consistent with nutrient enhancement observed within the centers of both eddies. Biological enhancement within each eddy was observed, which may have been a result of advection from source waters and/or a local response to upwelled nutrients. The influence of frontal variability and frontal eddies on nutrients and plankton at the front argues for the necessity for 3-D models to fully explain frontal behavior and its effects on biological responses. Ph.D. 2023-04-25T14:21:38Z 2023-04-25T14:21:38Z 2023-02 2023-03-01T14:02:54.743Z Thesis https://hdl.handle.net/1721.1/150558 In Copyright - Educational Use Permitted Copyright retained by author(s) https://rightsstatements.org/page/InC-EDU/1.0/ application/pdf Massachusetts Institute of Technology |
| spellingShingle | Hirzel, Andrew Joseph Physical and Biological Processes at the Middle Atlantic Bight Shelf-Break Front |
| title | Physical and Biological Processes at the Middle Atlantic Bight Shelf-Break Front |
| title_full | Physical and Biological Processes at the Middle Atlantic Bight Shelf-Break Front |
| title_fullStr | Physical and Biological Processes at the Middle Atlantic Bight Shelf-Break Front |
| title_full_unstemmed | Physical and Biological Processes at the Middle Atlantic Bight Shelf-Break Front |
| title_short | Physical and Biological Processes at the Middle Atlantic Bight Shelf-Break Front |
| title_sort | physical and biological processes at the middle atlantic bight shelf break front |
| url | https://hdl.handle.net/1721.1/150558 |
| work_keys_str_mv | AT hirzelandrewjoseph physicalandbiologicalprocessesatthemiddleatlanticbightshelfbreakfront |