Assessing Mesopelagic Zooplankton Food Web Connections at Ocean Station Papa Using Stable Isotope Analysis of Individual Amino Acids
| dc.contributor.advisor | Popp, Brian N. | |
| dc.contributor.author | Shea, Connor H. | |
| dc.contributor.department | Oceanography | |
| dc.date.accessioned | 2022-03-03T19:57:49Z | |
| dc.date.available | 2022-03-03T19:57:49Z | |
| dc.date.issued | 2021 | |
| dc.description.abstract | Constraining how mesopelagic zooplankton communities interact with sinking particle flux is central to building a quantitative understanding of how zooplankton affect the marine carbon cycle. Here, compound specific stable isotope analysis of amino acids is used to quantify food web connections and the contribution of small particles to the base of the mesopelagic zooplankton food web in the Subarctic Northeast Pacific. Samples were collected during the EXPORTS field campaign to Ocean Station Papa in late summer 2018. The δ15N values of source amino acids (δ15NSAA) in zooplankton and small (1-6 μm) particles are similar, which provides strong evidence that the base of the mesopelagic zooplankton food web is composed mainly of 1-6 μm particles. Sinking particulate matter captured in sediment traps, however, have δ15NSAA values which are lower and similar to what is measured in large (>51 μm) particles. These observations imply that small, suspended particles play an important role in the supply of carbon to the mesopelagic, and that this supply is likely not reflected in sediment trap-derived estimates of carbon flux. The δ15NSAA values of, and trophic position estimates for chaetognaths suggest that larger predatory taxa in the mesopelagic zone feed on vertically migrating individuals in addition to resident zooplankton at depth. When compared to results from similar studies across the North Pacific, we find that the importance of small particles to the base of the mesopelagic zooplankton food web is highest at sites with low migrant biomass, suggesting a reciprocal relationship between active transport and small particle flux as supplies of carbon to mesopelagic food webs. In addition, comparison of trophic position estimates based on the δ15N values of different combinations of source and trophic amino acids (glutamic acid and phenylalanine vs alanine and phenylalanine) suggests that prostistan heterotrophs are an active component of the zooplankton community down to at least 500 m, and that the length of the zooplankton food web decreases significantly with depth. Our results highlight the importance of small particles and active transport as a source of organic carbon to mesopelagic ecosystems in low productivity areas, emphasizing the need for further work towards distinguishing and quantifying multiple export pathways at mid-water depths. | |
| dc.description.degree | M.S. | |
| dc.identifier.uri | http://hdl.handle.net/10125/81659 | |
| dc.language | eng | |
| dc.publisher | University of Hawaii at Manoa | |
| dc.subject | Biological oceanography | |
| dc.title | Assessing Mesopelagic Zooplankton Food Web Connections at Ocean Station Papa Using Stable Isotope Analysis of Individual Amino Acids | |
| dc.type | Thesis | |
| dc.type.dcmi | Text | |
| local.identifier.alturi | http://dissertations.umi.com/hawii:11241 |
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