This is a scanned copy of the annual report on the scientific work undertaken at Davis Station in 1985. The report was written by J.B. Gallagher. Paraphrased from the introduction: This report describes the work undertaken at Davis from January 1985 to November 1985. Aims of the program: 1) Description of the seasonal circulation patterns within Ellis Fjord. This was done by measuring the salinity temperature profiles at selected stations down the length of the fjord, its entrance and the sea. 2) Origin, age, circulation and mixing rates of the meromictic basin. The deep waters of the meromictic basin have a salinity of approximately 1.4 the salinity of sea water. It's possible that this may be due to old sea water left behind after an isostatic uplift with subsequent concentration through evaporation. Calculation of mixing rates and description of the water circulation will explain why the basin is so stable. 3) Recent sedimentation rates within the meromictic basin. Sediment was collected from 110m for 137Cs analysis - the peak in the profile should indicate the age of that layer of sediment as 1963, during which atmospheric bomb tests released large quantities of 137Cs into the atmosphere. 4) Biogeochemistry of sulphur, iron, manganese, aluminium and carbon within the meromictic basin. The deep waters of the meromictic basin are anoxic (from 45m). This gave an ideal opportunity to study the cycling of the above redox active elements. 5) Collection and processing of water for trace element analysis and organometallics.

Ellis Fjord is a small, fjord-like marine embayment in the vestfold Hills, eastern Antarctica. Modern sediment input is dominated by a biogenic diatom rain, although aeolian, fluvial, ice-rafted, slumped and tidal sediments also make a minor contribution. In areas where bioturbation is significant relict glaciogenic sediments are reworked into the fine-grained diatomaceous sediments to produce poorly sorted fine sands and silts. Where the bottom waters are anoxic, sediments remain unbioturbated and have a high biogenic silica component. Three depositional and non-depositional facies can be recognised in the fjord: an area of non-deposition around the shoreline; a relict morainal facies in areas of low sedimentation and high bioturbation; and a basinal facies in the deeper areas of the fjord.

The sedimentological, chemical and isotopic characteristics of sediment cores from three slightly saline to hypersaline lakes (Highway, Ace and Organic Lakes) and two marine inlets (Ellis Fjord and Taynaya Bay) in the Vestfold Hills, Antarctica have been examined. Sections of the cores deposited in marine environments are characterised by uniform, regularly laminated, fine grained, organic-rich sediments, with uniform organic delta 13C values (-18.0 to 19.4 ppt vs. PDB) and sulfur contents. In contrast, sediments deposited in lacustrine environments are extremely heterogeneous, varying from finely laminated mat-like sequences to poorly sorted clastic-rich sediments. Authigenic monohydrocalcite and aragonite occur in some lake sediments. The delta 13C values of organic matter in the lacustrine sediments exhibit an extremely wide range (-10.5 to -25.3 ppt) that can be related to variations in physico-chemical conditions in the lake waters. Strongly negative organic-delta 13C values coupledwith high sulfur contents are indicative of an anoxic zone in the overlying lake waters, whereas less negative organic-delta 13C values coupled with low sulfur contents are indicative of well-mixed oxic conditions. Particularly high organic-delta 13C values result during high levels of microbial activity in the lakes, due to high rates of photosynthetic CO2 fixation. The large shifts in organic-delta 13C are not necessarily accompanied by any change in macroscopic sedimentological characteristics, illustrating the utility if isotopic investigations in these environments. The delta 13C composition of authigenic carbonate in hypersaline Organic Lake sediments provides a record of changes in palaeoproductivity, while the delta 18O of the carbonate provides information on rates of meltwater input and evaporation in the lake. 14C-dating suggests that Highway Lake was isolated from the sea by isostatic uplift at least 4600 years before present (BP) whereas Organic Lake was isolated at approximately 2700 years BP. Apparent emergence rates calculated from the 14C ages range from 1.0 to 2.1 mm per year. The 'reservoir effect' in the lacustrine and marine environments is variable, but probably does not exceed ~ 1000 years in any of the lakes examined.

Some scanning electron microscope images were taken of dinoflagellates sampled as part of this project. A catalogue of the images taken is provided as part of the download file at the provided URL. The images are currently held by the Electron Microscope Unit of the Australian Antarctic Division, but have not yet been entered into their electron microscope database (as at the 30th of April, 2004). From the abstracts of the referenced paper: The abundance and biomass of ciliates, dinoflagellates and heterotrophic and phototrophic nanoflagellates were determined at three sites along an ice-covered Antarctic fjord between January and November 1993. The water column showed little in the way of temperature and salinity gradients during the study period. In general, the protozooplankton exhibited a seasonal variation which closely mirrored that of chlorophyll a and bacterioplankton. The fjord mouth, which was affected by the greatest marine influences, consistently had the highest densities of ciliates and the most diverse community, with up to 18 species during the sampling period. Small aloricate ciliates were present throughout the year with Strobilidium spp. being dominant during the winter. Larger loricate and aloricate ciliates became more prominent during January and November, along with the autotrophic ciliate Mesodimium rubrun and two mixotrophic species (Strombidium wulffi and a type resembling Tontonia) suggesting evidence of species successions. Data on dinoflagellates were less extensive, but these protists showed greatest species diversity in the middle reaches of the fjord. A total of 13 species of dinoflagellate were recorded. Ciliates made a significant contribution to the biomass of the microbial community in summer, particularly in the middle and at the seaward end of the fjord. In winter, heterotrophic flagellates (HNAN) and phototrophic nanoflagellates (PNAN) were the dominant component of protistan biomass. In terms of percentage contribution to the microbial carbon pool, bacteria dominated during winter and spring. To the authors' knowledge, this is the first seasonal study of an Antarctic fjord. The Ellis Fjord is very unproductive compared to lower latitude systems, and supports low biomass of phytoplankton and microbial plankton during most of the year. This relates to severe climatic and seasonal conditions, and the lack of allochthonous carbon inputs to the system. Thus, high latitude estuaries may differ significantly from lower latitude systems, which generally rank among the most productive aquatic systems in the world. The fields in this dataset are: EMU Image Number Fiona Scott Image Number Species SEM Stub Number Location Collector