Date of Award

Spring 5-14-2016

Level of Access

Campus-Only Thesis

Language

English

Department

Ecology and Environmental Sciences

Advisor

Jasmine Saros

Second Committee Member

Michael Kinnison

Third Committee Member

Hamish Greig

Abstract

Water transparency has been declining coherently across lakes in Acadia National Park since 1995. This change in transparency has been accompanied by a thinning of the epilimnion in lakes across the Park. Using high frequency data from the Jordan Pond Buoy and additional modern and historical survey data, I found that observed changes in epilimnion thickness were largely due to changes in dissolved organic carbon (DOC) concentrations. Experiments were performed in Jordan Pond and Seal Cove Pond to simulate how changing light regimes with altered epilimnion thickness may have biological effects. Three light levels were tested to simulate current mixing conditions, as well as deeper or shallower conditions. The experiment revealed no effect of light in Jordan Pond; in Seal Cove Pond high light (i.e., a thinner epilimnion) resulted in lower chlorophyll a (Chl a), but little change in phytoplankton cell densities or species composition. This suggests that the altered light conditions that accompany changing epilimnion thickness may have stronger effects on phytoplankton physiology than abundance or diversity. Understanding the drivers of declining epilimnion thickness and how phytoplankton will respond to this change is essential to predict future water quality conditions in Acadia National Park and beyond.

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