Diatom identification and counts from 7 multicore locations on Kerguelen Plateau, Southern Ocean

Brief description

This dataset was collected as part of an honours project by Jessica Wilks at Macquarie University (submitted May 2012). The samples analysed were taken from an expedition conducted by Dr Leanne Armand in 2011 as part of the KEOPS2 mission (KErguelen: compared study of the Ocean and the Plateau in Surface water). During this mission 7 locations (A3-1, A3-2, E1-3, E14W2, NPF-L, R2 and TEW) around the Kerguelen Plateau were sampled for seafloor sediment. Each attached spreadsheet represents the data from one of these locations. Three tubes of sediment were taken for each location. The data within each spreadsheet is separate for the three tubes.

After the tubes of seafloor sediment were processed to remove organic material and carbonates (leaving nothing but siliceous material, primarily diatoms) slides were made with a small amount of material, three slides per tube of sediment. Diatoms were identified using a light microscope at 40x magnification. Approximately 400 frustules were counter per tube (ie per set of 3 slides) in order to represent the diversity of the species present. The number of each species or subspecies of diatom are tallied in the spreadsheets attached. Species identifications follow Armand et al 2008.

Other information in the attached spreadsheets includes the seafloor depth at the point of sampling, the distance from the Kerguelen shoreline at the point of sampling, the amount of suspended material used on each slide, the number of field of view (at 40X) viewed to count the quota of 400 diatom frustules, and the calculated number of frustules/ gram of dry sediment weight.

Counting protocol: centric frustules were counted only when 1) more than half of the frustule was intact; and 2) the frustule was clearly identifiable. If 1) but not 2) then the frustule was counted as "unidentified centric". For Rhizosolenia spp, frustules were couned if the apex was present and identifiable, otherwise it was counted as "R. unknown". Thalassiothrix and Tricotoxon were only counted if one end was present and identifiable. The number was later divided by 2, to give the number of complete frustules.

Abbreviations:
A. spp= Actinocyclus
As. spp= Asteromphalus
Az. spp= Azpeita
Ch. spp= Chaetoceros
Co. spp= Coscinodiscus
C. spp= Cocconeis
D. spp= Dactyliosen
E. spp= Eucampia
F. spp= Fragilariopsis
O. spp= Odontella
P. spp= Paralia
Po. spp= Porosira
R. spp= Rhizosolenia
Th. spp= Thalassionema
T. spp= Thalassiosira


Locations
A3-1, Kerguelen Plateau: -50.65333 S, 72.04 E
A3-2, Kerguelen Plateau: -50.64722 S, 72.07 E
E1-3, Kerguelen Plateau: -48.11667 S, 71.96667 E
E14W2, Kerguelen Plateau: -48.7775 S, 71.43833 E
NPF-L, Kerguelen Plateau: -48.62417 S, 74.81222 E
R2, Kerguelen Plateau: -50.39389 S, 66.69944 E
TEW, Kerguelen Plateau: -49.16083 S, 69.83389 E