Timescales of Growth Response of Microbial Mats to Environmental Change in an Ice-Covered Antarctic Lake

Biology

Ian Hawes¹  Dawn Y. Sumner⁴  Dale T. Andersen²  Anne D. Jungblut³ 

[1] Gateway Antarctica, University of Canterbury, Private Bag 4800, Christchurch, New Zealand;Carl Sagan Center for the Study of Life in the Universe, SETI Institute, 189 Bernado Avenue, Suite 100, Mountain View, CA 94043, USA; E-Mail:;Department of Life Sciences, The Natural History Museum, Cromwell Road, London, UK; E-Mail:;Department of Geology, University of California, Davis, CA 95616, USA; E-Mails:

关键词: cyanobacteria;    benthic communities;    microbial mat;    environmental change;    Antarctic lake;   

DOI  :  10.3390/biology2010151

来源: mdpi

【 摘 要 】

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, Oscillatoriaand 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.

【 授权许可】

CC BY   
© 2013 by the authors; licensee MDPI, Basel, Switzerland.