Microplankton dynamics in a perennially ice-covered Antarctic Lake - Lake Hoare

• Published in: Freshwater Biology
• Main Authors: Roberts, EC, Priscu, JC, Laybourn-Parry, J
• Format: Article in Journal/Newspaper
• Language: English
• Published: Blackwell Publishing Ltd 2004
• Subjects: Biological Sciences; Microbiology; Microbial Ecology; Antarctic; Hoare; Lake Hoare; McMurdo Dry Valleys; Antarc*; Antarctica
• Online Access: http://interscience.wiley.com; https://doi.org/10.1111/j.1365-2427.2004.01230.x; http://ecite.utas.edu.au/49065

1. Temporal and spatial variation in planktonic abundance, biomass and composition weredetermined in Lake Hoare (McMurdo Dry Valleys, Antarctica) over two summer seasons(199697 and 199798).2. Phototrophic nanoflagellates (PNAN) dominated planktonic biomass, with a meanmonthly biomass ranging between 27.3 and 40.4 lg C L)1. The deep chlorophyll maximumwas mainly composed of cryptophytes (>87% of total PNAN biomass) and varied in depthbetween 6 and 12 m.3. Maximum bacterial concentration was 11.8 105 cells mL)1. Bacterial abundanceshowed relatively little temporal variation, with the exception of a drop in numbers thatoccurred in late November of both years studied.4. Ciliates were the most successful heterotrophic protozoan group, with a mean monthlybiomass (1.23.2 lg C L)1) being typically at least double that of heterotrophic nanoflagellate(HNAN) biomass (0.10.7 lg C L)1).5. Microbial processes within this lake appear to be dominated by bottom up control. Therelative importance of allochthonous inputs into the lake (from the ice-cover and streamflow) and autochthonous recycling (by microzooplankton regeneration) are considered.6. Results from a horizontal transect indicate that the permanence of the main sample holemay have enhanced planktonic biomass over a relatively small spatial scale.