@article {4152,
	title = {Drivers of protistan community autotrophy and heterotrophy in chemically stratified Antarctic lakes},
	journal = {Aquatic Microbial Ecology},
	volume = {82},
	year = {2019},
	month = {01/2019},
	pages = {225 - 239},
	abstract = {<p>Single-celled, eukaryotic microorganisms, known as protists, are responsible for 2 important, yet opposing, metabolic activities within aquatic food webs. They are major primary producers and highly active predators in marine and fresh water systems. While genomics has accelerated in recent years for this taxonomically diverse group, our understanding of the metabolic capabilities of most protists remains limited. It is also poorly understood how protist trophic mode is affected by biotic and abiotic factors, and therefore it is difficult to predict how events such as global climate change will affect the balance between autotrophic and heterotrophic activities in protist communities. To address open questions regarding how protist metabolic versatility is influenced by their environment, we characterized the potential for carbon fixation versus organic carbon degradation using enzymatic assays (RubisCO and β-D-glucosaminidase, respectively) within the water columns of ice-covered lakes in McMurdo Dry Valleys (MDV), Antarctica. Steep physical and chemical gradients in the water columns, microorganism domination and minimal allochthonous inputs makes the MDV lakes uniquely suited to investigate environment-microbe interactions. Spatial trends in RubisCO and β-D-glucosaminidase activities were lake-specific and vertically stratified within the water columns. Moreover, bottom-up drivers controlling the activity of C-fixation vs. organic C-degradation among the MDV protist communities were distinct between the upper photic vs. the deep, aphotic zones. We conclude that differential controls over major C-cycling enzymes have important implications on the influence of environmental change on the carbon and nutrient cycles in the MDV lakes.</p>},
	keywords = {LTER-MCM, Antarctic lakes, Aquatic protists, Autotrophy, Heterotrophy, McMurdo Dry Valleys, RubisCO, β-D-glucosaminidase},
	issn = {0948-3055},
	doi = {10.3354/ame01891},
	url = {https://www.int-res.com/abstracts/ame/v82/n3/p225-239/},
	author = {Li, Wei and Dolhi-Binder, J and Cariani, ZE and Rachael M. Morgan-Kiss}
}
@article {4115,
	title = {Impact of nitrogen and phosphorus on phytoplankton production and bacterial community structure in two stratified Antarctic lakes: a bioassay approach},
	journal = {Polar Biology},
	volume = {40},
	year = {2017},
	month = {05/2017},
	chapter = {1007},
	abstract = {<p>Arctic, Antarctic, and alpine ecosystems are recognized as sensors and sentinels of global change. As a consequence of their high sensitivity to minor climatic perturbations, permanently ice-covered lakes located in the McMurdo Dry Valleys (MDV), Antarctica, represent end members in the global network of inland bodies of water. Episodic climatic events in the form of increased summer glacial melt result in inputs of organic sediment and nutrients from glacial streams to these closed basins. Phytoplankton communities residing in the oligotrophic water columns are highly responsive to pulses in nutrient availability; however, there is a lack of understanding on whether specific phytoplankton groups are more competitive during a summer flood event and how shifts in the phytoplankton community may influence heterotrophic bacteria. A bioassay approach in 3-l bottles was used to investigate the influence of inorganic nitrogen and phosphorus availability on planktonic communities from the oligotrophic upper waters of two chemically distinct MDV lakes (Lakes Bonney and Fryxell) which differ in their external inputs and water column N/P stoichiometry. While microbial community responses varied between lakes and were nutrient-dependent, stimulation of phytoplankton biomass and productivity across all treatments was strongly linked with increased abundance of a single phytoplankton phylum (Chlorophyta). Despite stimulation of phytoplankton growth, primary and bacterial productivity was generally uncoupled; however, shifts in bacterial community diversity were observed in bioassays amended with either P or NP. We suggest that climate-associated increases in phytoplankton production and concomitant shifts in diversity will influence MDV bacterial community structure by altering the availability and composition of autochthonous carbon for heterotrophic production.</p>},
	keywords = {LTER-MCM, Algal{\textendash}bacteria interactions, climate change, McMurdo Dry Valleys, Nutrient bioassay, Primary production},
	issn = {0722-4060},
	doi = {10.1007/s00300-016-2025-8},
	url = {https://link.springer.com/article/10.1007/s00300-016-2025-8},
	author = {Teufel, Amber G. and Li, Wei and Kiss, Andor J. and Rachael M. Morgan-Kiss}
}
