Graduation Year

2013

Document Type

Dissertation

Degree

Ph.D.

Degree Granting Department

Marine Science

Major Professor

Joseph J. Torres

Co-Major Professor

Pamela Hallock

Keywords

Climate Change, Ecology, Marine, Modelling, Ocean Acidification, Physiology

Abstract

Pteropods are holoplanktonic gastropod molluscs found globally. Although species diversity is greater at lower latitudes, species abundance is greater at temperate and polar latitudes. Declines in pteropod populations have not only been correlated to declines of their major predators, but pteropods have also been used as bioindicators of global environmental changes such as ocean acidification. With high latitude abundances, pteropods provide significant sustenance for species such as the Atlantic salmon in the Atlantic Ocean and Pleuragramma antarcticum in the Southern Ocean. Because pteropods eat phytoplankton and other pteropods, factors that affect pteropod abundance influence many trophic levels. This dissertation explores ecological, physiological and trophodynamic relationships of pteropods when considering the influences of environmental factors observed to be altering the western Antarctic Peninsula's marine ecosystem. Over the last few decades very few studies have reported the distributions of pteropods along the western Antarctic Peninsula, in particular south of the Gerlache Strait. The ecological study provided the first detailed report of the pteropods Spongiobranchaea australis and Clione antarctica along the western Antarctic Peninsula south of the Gerlache Strait, and their local distribution was correlated to the region's major water masses and mesoscale water mass circulation. The physiological study of S. australis and C. antarctica yielded the first account of their metabolism, ratios of oxygen consumed to nitrogen excreted, proximate body composition, primary substrates oxidized, and enzymatic activities along the study's latitudinal gradient; the first report of S. australis' physiology anywhere around Antarctica. The final chapter utilized a comprehensive Ecopath with Ecosim model of the western Antarctic Peninsula's marine ecosystem. The model was used to explore the trophodynamic significance of pteropods within their polar marine ecosystem as well as changes in whole ecosystem trophodynamics by employing various climate change scenarios expected to alter the Peninsula's marine ecosystem over the next 40 years. The sum of these studies provides a foundation for exploring pteropods as bioindicators of environmental change along the western Antarctic Peninsula, a region currently experiencing considerable climate anomalies.

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