Sea Ice Biota of Coastal Eastern Antarctica

Brief description

The distribution and abundance of ice-associated copepods in the fast ice of the Australian Antarctic Territory were investigated over a distance of approximately 650 km between October and December 1995. The six sites where collections were made were: offshore from Mawson station, Larsemann Hills (including Nella Bay), Rauer Islands (ice edge near Filla Is), O'Gorman Rocks and Bluff Island near Davis Station, and Murphy Rocks in the northern Vestfold Hills.

Ice cores were obtained using SIPRE ice augers. Five to ten cores were collected along transects several km in length. Thickness of sea ice and snow cover were measured at each sampling site. Chlorophyll a concentrations were determined for each core. Copepods were isolated from the melted core water and identified and counted. Zooplankton tows were also made at each site where
cores were collected.

Nine species of copepods were identified from the cores. However, of these, only three were recorded regularly: Paralabidocera antarctica, Drescheriella glacialis and Stephos longipes. The abundance of copepods ranged between 0 and 147/L. The highest densities were recorded at the Larsemann Hills and the lowest at Murphy Rocks. Within the cores, the highest abundances were found in the bottom 10 cm of ice, irrespective of the species. Chlorophyll a concentrations ranged between 0.9 and 373 mg/m3.

Data available: excel files containing sampling dates, sampling sites and abundances (number per L) of three dominant sea ice copepods, Paralabidocera antarctica, Drescheriella glacialis, Stephos longipes. Data are presented for developmental stages (nauplii, copepodites and adults) where available. Totals are also provided. Vertical distribution in some cores is also provided. Chlorophyll a concentrations (ug/L) provided for most sites. Detailed information about each of the spreadsheets is provided below:

The chlorophyll spreadsheet shows chlorophyll concentrations for 5 sites in the AAT. The column headings are:
core - reference number of the core collected
subsection - depth in the core in cm
volume - vol of melted core water
volume added - 1 L of filtered seawater for melting
% original - amount of total that core water represents (i.e. minus the 1L added)
aliquot - volume subsampled for chlorophyll analysis
acetone - amount added (mL) for extraction
750, 664, 647, 630 - wavelengths where absorbance was measured
chloro a - amount of chlorophyll a in the sample
ug/L - chloro a expressed as a concentration

The spatial spreadsheet shows species abundances of three copepods at 4 sites
N1 to NVI - nauplius stage 1 to 6 of a species
CI to CVI - copepodite stage 1 to 6 of a species
F or M - female or male of copepodite stage 5 or 6
1,1 etc - cores 1 and 2 from site 1 within a major location (e.g. 2 cores close together in the Larsemann Hills)

The temporal spreadsheet shows abundances over time at 2 sites (O'Gorman Rocks, Bluff Is) near Davis and two species (Paralabidocera antarctica and Drescheriella glacialis) on several sampling dates
N1 to N3 - total nauplii in each of three cores (i.e. not separated into stages as above)
C1 to C3 - total copepodites
A1 to A3 - total adults
Then at the bottom are the means of each three cores.

Lineage

Progress Code: completed

Statement: Short term spatial coverage of sea ice between Mawson and Davis Stations (approximately 650 km). Complete species lists of copepods and other invertebrates found in the sea ice.