Date

2018

Department or Program

Biological Sciences

Primary Wellesley Thesis Advisor

Rachel Stanley

Additional Advisor(s)

Jaclyn Hatala Matthes

Additional Advisor

Vanja Klepac-Ceraj

Additional Advisor

Yue Hu

Abstract

Oceans account for more than 25% of anthropogenic CO2 removal from the atmosphere. Changes in our global climate have affected the Arctic Ocean in particular, resulting in increasing rates of warming and record-low sea ice extent, which for example, in the summer of 2012, was only half of the average over the previous three decades. It is unclear how these changes in the Arctic Ocean may affect biological productivity, which is one of the main drivers of the oceanic carbon cycle as CO2is consumed through photosynthesis and released through respiration. In order to investigate how these changes may influence the efficacy of the Arctic Ocean as a carbon sink, we calculated the gross oxygen production (GOP), which is the rate of total photosynthesis, and the net community production (NCP), which is the rate of photosynthesis minus community respiration and thus represents the strength of the carbon sink. The chemical gas tracers, triple oxygen isotopes and O2/Ar ratios, as measured in samples from the surface waters of the Beaufort Gyre region of the Canada Basin, were used to quantify gross oxygen production and net community production, respectively, in late summer and early fall over six years (2011-2016). We examined the effects of location, ice cover, chlorophyll-a, season, and more to better understand the collective impact of these physical conditions on biological productivity rates. Over these six years, mean GOP rates ranged from 9.1 ± 1 mmol O2 m-2 d-1 to 40 ± 4 mmol O2 m-2d-1 and mean NCP rates ranged from 1.1 ± 0.2 mmol O2 m-2 d-1 to 2.5 ± 0.2 mmol O2 m-2 d-1. Analyzing inter-annual variations in these rates can enlighten our understanding of how dramatic changes in the global climate may impact the ability of this region in the Arctic Ocean to remove carbon dioxide from the atmosphere.

Available for download on Saturday, April 25, 2020

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