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Timescales of Growth Response of Microbial Mats to Environmental Change in an Ice-Covered Antarctic Lake
Gateway Antarctica, University of Canterbury, Private Bag 4800, Christchurch, New Zealand
Department of Geology, University of California, Davis, CA 95616, USA
Carl Sagan Center for the Study of Life in the Universe, SETI Institute, 189 Bernado Avenue, Suite 100, Mountain View, CA 94043, USA
Department of Life Sciences, The Natural History Museum, Cromwell Road, London, UK
* Author to whom correspondence should be addressed.
Received: 15 November 2012; in revised form: 19 December 2012 / Accepted: 20 December 2012 / Published: 25 January 2013
Abstract: Lake Vanda is a perennially ice-covered, closed-basin lake in the McMurdo Dry Valleys, Antarctica. Laminated photosynthetic microbial mats cover the floor of the lake from below the ice cover to >40 m depth. In recent decades, the water level of Lake Vanda has been rising, creating a “natural experiment” on development of mat communities on newly flooded substrates and the response of deeper mats to declining irradiance. Mats in recently flooded depths accumulate one lamina (~0.3 mm) per year and accrue ~0.18 µg chlorophyll-a cm−2 y−1. As they increase in thickness, vertical zonation becomes evident, with the upper 2-4 laminae forming an orange-brown zone, rich in myxoxanthophyll and dominated by intertwined Leptolyngbya trichomes. Below this, up to six phycobilin-rich green/pink-pigmented laminae form a subsurface zone, inhabited by Leptolyngbya, Oscillatoria and Phormidium morphotypes. Laminae continued to increase in thickness for several years after burial, and PAM fluorometry indicated photosynthetic potential in all pigmented laminae. At depths that have been submerged for >40 years, mats showed similar internal zonation and formed complex pinnacle structures that were only beginning to appear in shallower mats. Chlorophyll-a did not change over time and these mats appear to represent resource-limited “climax” communities. Acclimation of microbial mats to changing environmental conditions is a slow process, and our data show how legacy effects of past change persist into the modern community structure.
Keywords: cyanobacteria; benthic communities; microbial mat; environmental change; Antarctic lake
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Hawes, I.; Sumner, D.Y.; Andersen, D.T.; Jungblut, A.D.; Mackey, T.J. Timescales of Growth Response of Microbial Mats to Environmental Change in an Ice-Covered Antarctic Lake. Biology 2013, 2, 151-176.
Hawes I, Sumner DY, Andersen DT, Jungblut AD, Mackey TJ. Timescales of Growth Response of Microbial Mats to Environmental Change in an Ice-Covered Antarctic Lake. Biology. 2013; 2(1):151-176.
Hawes, Ian; Sumner, Dawn Y.; Andersen, Dale T.; Jungblut, Anne D.; Mackey, Tyler J. 2013. "Timescales of Growth Response of Microbial Mats to Environmental Change in an Ice-Covered Antarctic Lake." Biology 2, no. 1: 151-176.