Timescales of growth response of microbial mats to environme
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TitleTimescales of growth response of microbial mats to environmental change in an ice-covered Antarctic lakeAbstractLake 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 greater than 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 greater than 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. Copyright 2013 by the authors; licensee MDPI, Basel, Switzerland.AcknowledgementsThis study was supported by funds from the NASA Exobiology Programme (NNX08AO19G) and the New Zealand Foundation for Research, Science and Technology (CO1X0306). We would like to acknowledge the logistic support of the US Antarctic Programme and Antarctica New Zealand and ongoing support and interaction with the Taylor Valley Long Term Ecological Research Programme (NSF grant 115245). The manuscript was much improved by comments from three anonymous reviewers.
TypeArticleCitationHawes, I., Sumner, D., Andersen, D., Jungblut, A. and Mackey, T. (2013). Timescales of growth response of microbial mats to environmental change in an ice-covered Antarctic lake. Biology, 2(1): 151-176 IdentifierHawes2013Relevancerank5
