In conjunction with the Long Term Ecological Research (LTER) project in the McMurdo Dry Valleys of Antarctica, lakes were monitored for microzooplankton by a team based out of the University of Nottingham (led by Johanna Laybourn-Parry). This dataset shows numbers of ciliates, bacteria, heterotrophic nanoflagellates, and phototrophic nanoflagellates found at various depths in Lake Fryxell.
Water was collected using either a Kemmerer bottle or a Van Dorn sampler lowered through a hole in the 4-m-thick ice with a Jiffy-drill in January 1992 and in January 1994 at a center station (depth 18.5 m). Samples were taken at 1-m intervals down to 12 m into the anoxic zone. In 1992, 250-ml subsamples were fixed in Lugol's iodine for the analysis of ciliates, and other aliquots fixed in glutaraldehyde for bacterial counts. In1994, 1.1-l samples were fixed in buffered glutaraldehyde for protozoological and bacterial analysis. These were kept refrigerated in the dark and flown to Australia or New Zealand for immediate analysis. Both fixatives are regarded as reliable for protistan analysis provided samples are analysed within a few months of collection. However, in our experience while Lugol's iodine is considered best for preserving abundance, it does cause more cell distortion of some species than glutaraldehyde, which gives better preservation of ciliates in freshwater samples. One liter of water from each depth was preserved in Lugol's iodine for phytoplankton counts. Temperature was measured with a (YSI) Yellow Springs Instruments 54 meter and probe, and conductivity with a Radiometer Conductivity meter. Ten milliliters of the buffered glutaraldehyde-fixed material was stained with DAPI, and filtered onto a 0.2-microm black polycarbonate filter, and bacterial numbers were counted under epifluorescence microscopy using UV excitation. Fifty milliliters was stained with DAPI, filtered onto 1.0-microm polycarbonate filters and viewed under epifluorescence microscopy using both blue and UV filters to determine heterotrophic and autotrophic flagellate abundances. The larger protozooplankton in each 1-l sample of glutaraldehyde-fixed water were concentrated by settling, stained with bromophenol blue and counted in Sedgewick-Rafter counting chambers under DIC microscopy at x320. Detailed analysis was undertaken under higher magnification using both DIC and phase microscopy. For phytoplankton analysis between 5 and 50 ml was subsampled. These phytoplankton were settled and enumerated using the inverted microscope method of Utermohl.
Metadata completed in 2016.
Data migrated to the Drupal Ecological Information Management System (DEIMS in 2014 (San Gil)
Data for this file was submitted by Johanna Laybourn-Parry to the data manager at INSTAAR on October 21, 1998. Files were sent via e-mail as well as a hard copy. The original version of the file is stored on the Unix system in "/data1/data/lakes/plankton/laybourn-parry/Fryxell". Upon arrival at INSTAAR, the data manager reformatted the file to present it in a relational mode. This was done using Microsoft Access. It was then exported in comma delimited ascii and MS-DOS text format to present on the web. Links to these files are provided above.