<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Trista J. Vick-Majors</style></author><author><style face="normal" font="default" size="100%">John C. Priscu</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Bacterioplankton productivity in lakes of the Taylor Valley, Antarctica, during the polar night transition</style></title><secondary-title><style face="normal" font="default" size="100%">Aquatic Microbial Ecology</style></secondary-title><short-title><style face="normal" font="default" size="100%">Aquat. Microb. Ecol.</style></short-title></titles><dates><year><style  face="normal" font="default" size="100%">2012</style></year><pub-dates><date><style  face="normal" font="default" size="100%">12/2013</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.int-res.com/abstracts/ame/v68/n1/p77-90</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">68</style></volume><pages><style face="normal" font="default" size="100%">77 - 90</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;&lt;span style=&quot;color: rgb(51, 51, 51); font-family: Arial, Helvetica, Geneva, Helvetica, sans-serif; font-size: 12px; line-height: 18px; text-align: justify;&quot;&gt;Research on the lakes of the McMurdo Dry Valleys, Antarctica, is typically conducted during the period of 24 h sunlight (October to January) when logistical support is readily available. As part of the International Polar Year initiative, we obtained logistical support to study microbial dynamics in the permanently ice-covered lakes of the Taylor Valley during the transition from 24 h of sunlight to the complete darkness of the polar night (mid-April). Our study focused on the perennially ice-covered lakes Fryxell (FRX), East Lobe Bonney (ELB), and West Lobe Bonney (WLB), all of which are chemically stratified and have food webs dominated by microorganisms. Depth-integrated bacterioplankton productivity (BP; leucine incorporation [Leu] and thymidine incorporation [TdR]) in the lakes ranged from 1.2 to 3.4 mg C m&lt;/span&gt;&lt;span style=&quot;font-size: smaller; position: relative; bottom: 0.4em; color: rgb(51, 51, 51); font-family: Arial, Helvetica, Geneva, Helvetica, sans-serif; line-height: 18px; text-align: justify;&quot;&gt;&amp;minus;2&lt;/span&gt;&lt;span style=&quot;color: rgb(51, 51, 51); font-family: Arial, Helvetica, Geneva, Helvetica, sans-serif; font-size: 12px; line-height: 18px; text-align: justify;&quot;&gt;&amp;nbsp;d&lt;/span&gt;&lt;span style=&quot;font-size: smaller; position: relative; bottom: 0.4em; color: rgb(51, 51, 51); font-family: Arial, Helvetica, Geneva, Helvetica, sans-serif; line-height: 18px; text-align: justify;&quot;&gt;&amp;minus;1&lt;/span&gt;&lt;span style=&quot;color: rgb(51, 51, 51); font-family: Arial, Helvetica, Geneva, Helvetica, sans-serif; font-size: 12px; line-height: 18px; text-align: justify;&quot;&gt;. Overall, summer was characterized by relatively high rates of BP and photoautotrophic primary productivity. Rapid decreases in photosynthetically active radiation marked a subsequent transition period, which was characterized by variable cell counts and decreasing Leu:TdR ratios (ratios &amp;gt;1 signify a physiological shift from growth to maintenance mode). Finally, cell counts decreased and Leu:TdR increased by as much as 280% during the fall, revealing a distinct change in the physiological state of the bacterioplankton as light-mediated primary productivity ceased. Our data reveal that the shift in physiological state may result from a switch from contemporary phytoplankton-excreted carbon to other sources of dissolved organic carbon, which can support the bacterioplankton populations through the winter.&lt;/span&gt;&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">1</style></issue></record></records></xml>