Open AccessMicrobial dynamics and flagellate grazing during transition to winter in L akes H oare and B onney, A ntarctica
Author(s) -
Thurman Jill,
Parry Jacqueline,
Hill Philip J.,
Priscu John C.,
Vick Trista J.,
Chiuchiolo Amy,
LaybournParry Johanna
Publication year - 2012
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2012.01423.x
Subject(s) - grazing , biology , flagellate , heterotroph , autotroph , ecology , plankton , mixotroph , bacteria , botany , genetics
The planktonic microbial communities of L akes H oare and B onney were investigated during transition into winter. We hypothesized that the onset of darkness induces changes in the functional role of autotrophic and heterotrophic microplankton. Bacteria decreased in L ake H oare during M arch– A pril, while in L ake B onney bacterial abundances varied. Heterotrophic nanoflagellates ( HNAN ), phototrophic nanoflagellates ( PNAN ) and ciliates showed no marked decline with the onset of winter. PNAN outnumbered HNAN in both lakes. Grazing rates of HNAN in L ake H oare ranged up to 30.8 bacteria per cell day −1 . The HNAN community grazed between 3.74 and 36.6 ng of bacterial carbon day −1 . Mixotrophic PNAN had grazing rates up to 15.2 bacteria per cell day −1 , and their daily community grazing exceeded bacterial production. In L ake B onney E ast, PNAN grazing rates ranged up to 12.48 bacteria per cell day −1 and in L ake B onney W est up to 8.16 bacteria per cell day −1 . As in L ake H oare, the mixotrophic PNAN grazing rates (up to 950 ng C day −1 ) usually exceeded bacterial production. HNAN grazing rates were generally similar to those in L ake H oare. As winter encroaches, these lakes move progressively towards heterotrophy and probably function during the winter, enabling populations to enter the short austral summer with actively growing populations.