Browsing by Subject "Currents"
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Item Estimation and Fate of New Production in the Marine Environment(2014-06-03) McInnes, Allison SkinnerThe fate of carbon in the ocean determines both the amount of CO_(2) that can be sequestered and the amount of sustainable biomass. Compartmentalization into new and regenerated production allows a first order estimate of carbon available to the local community versus the amount exported. The goal of this project was to study sources and sinks of production in order to test the general hypothesis that new production is underestimated in the marine environment. Specifically we looked at pulsed new nutrients and the effect on the ecosystem, the effect of currents on our measurements and estimates of export (equivalent to new production), and finally development of a new method which will allow in situ determination of new production in the majority of the global ocean. Specifically, the role of a Pacific herring spawn was investigated as an important stimulant to ecosystem wide carbon and nitrogen cycling in Simpson Bay, Alaska. A consistent pattern was observed each year: a large bloom in June corresponded to the timing of the herring spawn and low nutrients, low phytoplankton diversity, and high POC concentrations; elucidating a previously unidentified pulse of new nutrients to the system. Estimates of carbon export are affected by the physical environment. The model presented and validated herein is used to improve our understanding of C export by including the effect of horizontal transport. We show that measurements of export to shallow water traps are less impacted by currents than deep traps. Spatial extent of variable primary production necessary to affect deep water traps is greater, as such, over half of the traps analyzed in this study are affected by up-current productivity regimes. A method to simultaneously quantify the C and N fixing community in the same sample was developed, eliminating many assumptions introduced when using different techniques and incubations. Cultured and environmental samples were successfully hybridized using TSA-FISH. Strong correlations between positively tagged community abundance and ^(14)C/^(15)N measurements are presented. The findings of this work support the general hypothesis that new production is under-accounted for in marine systems.Item It's the sea, let it be?! : a Legacy Cycle curriculum(2011-12) Cooper, Cynthia Diane; Wilson, Clark R.; Ellins, Katherine K.It is incumbent upon teachers to reach out to students through methods that capitalize on the students' own motivations. Because of the diversity of self-referential personal styles of learning, reaching every student with a cookie-cutter approach to teaching is nearly impossible. This report explores the application of a type of problem-based learning known as "Legacy Cycles" that apply web technology to answer challenges presented as scenarios. The scenarios give students a similar experience to scientists pursuing investigation and research. Students then search for answers to questions, learn more about the processes being taught with hands-on activities, and prepare a product to demonstrate mastery of the content. In this example of the Legacy Cycle, three challenges are used to teach concepts of density, ocean currents and plastic pollution.Item Observations of Physical Properties and Currents in the Northern Gulf of Mexico during Summer, 2002-2004, and Currents from January to July 2006(2010-07-14) Lalime, MichaelMany processes in the ocean are interrelated. The direction with which an eddy rotates will determine if nutrients are moved closer to the surface where they can be utilized by plankton to increase the base of the food chain, or it can restrict growth by causing the surface layer of nutrient poor water to deepen below the photic layer. The direction of current flow will also affect the temperature structure, which is a contributing factor in the density of water. A change in density can act as a barrier between the surface and deeper waters, effectively isolating the surface from deep waters. It is important to understand the physical properties in a study area in order to understand the dynamics controlling the distributions of nutrients, which influence the distribution of plankton, which influences the distribution of predator species like squid and whales. The Sperm Whale Seismic Study (SWSS) tracked the locations of sperm whales in the Gulf of Mexico. This study seeks to describe the physical environment in which they live. To that end, various physical properties observed during the SWSS cruises were processed and used in conjunction with sea surface height (SSH) fields from satellite altimetry data. The data from different years and from the same years are used to provide descriptions of the physical environment present during the SWSS cruises and how that environment changed between cruises. A time-series of currents, collected over a six month time period in 2006, is included to document how the currents are influenced by different processes found along the continental slope in the northern Gulf of Mexico. The findings indicate the observed currents are related to local SSH features. Temperature structure can be influenced throughout the upper 1000 m by these SSH features. The temperature structure is stable over time but depends on local SSH features. Properties nearer to the surface are more variable than at depth. Although the overlying wind field most likely influences the currents at 51 m no correlation between winds observed at the Brutus platform and currents observed at 51 m at the Ocean Star platform was found.