02691nas a2200229   4500008004100000022001400041245015500055210006900210260001200279490000700291520189400298653003402192653001902226653002402245653002202269653002302291100002202314700001202336700002002348700002902368856006402397       2017                        eng d  a0722-406000aImpact of nitrogen and phosphorus on phytoplankton production and bacterial community structure in two stratified Antarctic lakes: a bioassay approach0 aImpact of nitrogen and phosphorus on phytoplankton production an  c05/20170 v403 a<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>10aAlgal–bacteria interactions10aclimate change10aMcMurdo Dry Valleys10aNutrient bioassay10aPrimary production1 aTeufel, Amber, G.1 aLi, Wei1 aKiss, Andor, J.1 aMorgan-Kiss, Rachael, M.  uhttps://link.springer.com/article/10.1007/s00300-016-2025-8