Zooplankton Community Composition and Grazing in the Amazon River Plume and Western Tropical North Atlantic Ocean
Large river plumes and frontal zones are important physical features influencing plankton distribution in the marine environment. In the western tropical North Atlantic Ocean (WTNA) the Amazon River plume may extend over an area reaching 1.5 x 106 km2. The freshwater plume creates a low-density lens...
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ftwilliammarycol:oai:scholarworks.wm.edu:etd-1052 2024-06-23T07:55:05+00:00 Zooplankton Community Composition and Grazing in the Amazon River Plume and Western Tropical North Atlantic Ocean Conroy, Brandon J. 2016-01-01T08:00:00Z application/pdf https://scholarworks.wm.edu/etd/1477068157 https://doi.org/10.21220/V53K52 https://scholarworks.wm.edu/context/etd/article/1052/viewcontent/Conroy_vims_0261D_10007.pdf English eng W&M ScholarWorks https://scholarworks.wm.edu/etd/1477068157 doi:10.21220/V53K52 https://scholarworks.wm.edu/context/etd/article/1052/viewcontent/Conroy_vims_0261D_10007.pdf © The Author http://creativecommons.org/licenses/by/4.0/ Dissertations, Theses, and Masters Projects Ecology and Evolutionary Biology Marine Biology Oceanography text 2016 ftwilliammarycol https://doi.org/10.21220/V53K52 2024-06-05T03:27:56Z Large river plumes and frontal zones are important physical features influencing plankton distribution in the marine environment. In the western tropical North Atlantic Ocean (WTNA) the Amazon River plume may extend over an area reaching 1.5 x 106 km2. The freshwater plume creates a low-density lens in the surface 25m and supplies silicon and phosphorus to the WTNA. These physical and chemical gradients create an ideal environment for large-scale blooms of diatom diazotroph associations (DDAs), a symbiotic relationship between nitrogen-fixing cyanobacteria and chain-forming diatoms. While the physical and chemical properties of the plume with regard to influences on phytoplankton have been reported, zooplankton distributions and the fate of enhanced primary production in the plume are largely unknown. I investigated mesozooplankton (>200 μm) composition and grazing in the Amazon River plume-influenced WTNA in spring (May-June 2010) and fall (Sept.-Oct. 2011). Changes in zooplankton distribution and grazing occurred over the sea surface salinity (SSS) gradient from low salinity and mesohaline plume waters to high salinity oceanic waters. Distinct communities were identified in each season along the salinity gradient with several taxa primarily constrained in the surface plume waters (e.g., Lucifer faxoni). The plume appears to function as an “extended estuaryâ€, with a number of taxa (e.g., decapods, euphausiids, and fish larvae) utilizing the plume as a nursery habitat or dispersal mechanism for larval stages. Mesozooplankton grazing was elevated in plume waters compared to oceanic waters and was 2-3 times higher in the fall vs. spring. These patterns suggest a lag in the peak mesozooplankton abundance and grazing in response the observed spring DDA bloom, at least in low salinity plume waters. Comparison of micro- and mesozooplankton grazing along the SSS gradient supported a transition from an “export†food web in waters with SSS < 33 where mesozooplankton grazing dominated and potential for export ... Text North Atlantic W&M ScholarWorks |
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Open Polar |
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W&M ScholarWorks |
op_collection_id |
ftwilliammarycol |
language |
English |
topic |
Ecology and Evolutionary Biology Marine Biology Oceanography |
spellingShingle |
Ecology and Evolutionary Biology Marine Biology Oceanography Conroy, Brandon J. Zooplankton Community Composition and Grazing in the Amazon River Plume and Western Tropical North Atlantic Ocean |
topic_facet |
Ecology and Evolutionary Biology Marine Biology Oceanography |
description |
Large river plumes and frontal zones are important physical features influencing plankton distribution in the marine environment. In the western tropical North Atlantic Ocean (WTNA) the Amazon River plume may extend over an area reaching 1.5 x 106 km2. The freshwater plume creates a low-density lens in the surface 25m and supplies silicon and phosphorus to the WTNA. These physical and chemical gradients create an ideal environment for large-scale blooms of diatom diazotroph associations (DDAs), a symbiotic relationship between nitrogen-fixing cyanobacteria and chain-forming diatoms. While the physical and chemical properties of the plume with regard to influences on phytoplankton have been reported, zooplankton distributions and the fate of enhanced primary production in the plume are largely unknown. I investigated mesozooplankton (>200 μm) composition and grazing in the Amazon River plume-influenced WTNA in spring (May-June 2010) and fall (Sept.-Oct. 2011). Changes in zooplankton distribution and grazing occurred over the sea surface salinity (SSS) gradient from low salinity and mesohaline plume waters to high salinity oceanic waters. Distinct communities were identified in each season along the salinity gradient with several taxa primarily constrained in the surface plume waters (e.g., Lucifer faxoni). The plume appears to function as an “extended estuaryâ€, with a number of taxa (e.g., decapods, euphausiids, and fish larvae) utilizing the plume as a nursery habitat or dispersal mechanism for larval stages. Mesozooplankton grazing was elevated in plume waters compared to oceanic waters and was 2-3 times higher in the fall vs. spring. These patterns suggest a lag in the peak mesozooplankton abundance and grazing in response the observed spring DDA bloom, at least in low salinity plume waters. Comparison of micro- and mesozooplankton grazing along the SSS gradient supported a transition from an “export†food web in waters with SSS < 33 where mesozooplankton grazing dominated and potential for export ... |
format |
Text |
author |
Conroy, Brandon J. |
author_facet |
Conroy, Brandon J. |
author_sort |
Conroy, Brandon J. |
title |
Zooplankton Community Composition and Grazing in the Amazon River Plume and Western Tropical North Atlantic Ocean |
title_short |
Zooplankton Community Composition and Grazing in the Amazon River Plume and Western Tropical North Atlantic Ocean |
title_full |
Zooplankton Community Composition and Grazing in the Amazon River Plume and Western Tropical North Atlantic Ocean |
title_fullStr |
Zooplankton Community Composition and Grazing in the Amazon River Plume and Western Tropical North Atlantic Ocean |
title_full_unstemmed |
Zooplankton Community Composition and Grazing in the Amazon River Plume and Western Tropical North Atlantic Ocean |
title_sort |
zooplankton community composition and grazing in the amazon river plume and western tropical north atlantic ocean |
publisher |
W&M ScholarWorks |
publishDate |
2016 |
url |
https://scholarworks.wm.edu/etd/1477068157 https://doi.org/10.21220/V53K52 https://scholarworks.wm.edu/context/etd/article/1052/viewcontent/Conroy_vims_0261D_10007.pdf |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_source |
Dissertations, Theses, and Masters Projects |
op_relation |
https://scholarworks.wm.edu/etd/1477068157 doi:10.21220/V53K52 https://scholarworks.wm.edu/context/etd/article/1052/viewcontent/Conroy_vims_0261D_10007.pdf |
op_rights |
© The Author http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.21220/V53K52 |
_version_ |
1802647506730876928 |