Zooplankton play an important role in global biogeochemistry and their secondary production supports valuable fisheries of the world’s oceans. Coupled physical-biogeochemical models (PBMs) provide a unique oceanographic research tool for studying zooplankton on basin and global scales since zooplankton cannot currently be estimated using remote sensing techniques. However, evaluating the accuracy of zooplankton abundance estimates from PBMs has been a major challenge as a result of sparse ship-based observations. Consequently, zooplankton dynamics have been under studied and under validated in PBMs. In this study, we configure a PBM for the Gulf of Mexico (GoM) and validate simulated zooplankton fields against an extensive combination of in situ biomass and rate measurements. We find that spatial variability in mesozooplankton biomass observed in a multi-decadal database for the northern GoM is well resolved by the model with a statistically significant (p < 0.05) correlation of 0.74. In terms of community composition, the model estimates that large zooplankton (LZ) and predatory zooplankton (PZ) functional groups makes up approximately 40% and 60% of the simulated mesozooplankton biomass respectively, which is further supported by ship-based measurements. Once validated the model was used to investigate mesozooplankton diet and secondary production. Model results of LZ dietary composition suggests that herbivory is the dominant feeding pathway whereas PZ dietary composition is largely carnivorous. Dietary composition is found to be less binary in the oligotrophic GoM where LZ and PZ feed on a combination of phytoplankton and zooplankton. We discuss how already low mesozooplankton biomass in the oligotrophic Gulf (~0.04 mmol N m-3) may become further reduced in the future with important impacts on food availability for higher planktivorous trophic levels such as pelagic larval fish. Such reductions could be expected from increases in thermal stratification as a result of a warming ocean and ensuing increases in bottom-up ecosystem limitation. / A Thesis submitted to the Department of Earth, Ocean and Atmospheric Science in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester 2019. / April 17, 2019. / bio-physical model, Gulf of Mexico, larval fish, offline modeling, physical-biogeochemical model, zooplankton / Includes bibliographical references. / Michael Stukel, Professor Co-Directing Thesis; Eric Chassignet, Professor Co-Directing Thesis; Steven Morey, Committee Member; Sven Kranz, Committee Member; Nicholas Cogan, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_709826 |
| Contributors | Shropshire, Taylor A. (Taylor Adam) (author), Stukel, Michael R. (Professor Co-Directing Thesis), Chassignet, Eric P. (Professor Co-Directing Thesis), Morey, Steven L. (Committee Member), Kranz, Sven Alexander (Committee Member), Cogan, Nicholas G. (Committee Member), Florida State University (degree granting institution), College of Arts and Sciences (degree granting college), Department of Earth, Ocean and Atmospheric Science (degree granting departmentdgg) |
| Publisher | Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text, master thesis |
| Format | 1 online resource (54 pages), computer, application/pdf |
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