Biology of Antarctic Algae
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Metadata record for data from ASAC Project 102 See the link below for public details on this project. From the abstracts of some of the referenced papers: Six species of marine microalgae, namely Phaeodactylum tricornutum Bohlin, Dunaliella tertiolecta Butcher, Isochrysis galbana Parke, Porphyridium purpureum (Bory) Ross, Chroomonas sp., and Oscillatoria woronichinii Anis., have been examined with respect to their gas exchange characteristics and the inorganic carbon species taken up by the cells from the bulk medium. All species showed a high affinity, in photosynthesis, for inorganic carbon and low CO2 compensation concentrations. Such data are suggestive of operation of a 'CO2-concentrating mechanism' in these microalgae. Direct measurements of internal organic carbon pools in four of the species studied confirm this (O. woronichinii and Chroomonas were not tested). By comparison of achieved photosynthetic rates with calculated rates of CO2 supply from the dehydration of bicarbonate, it was shown that Phaeodactylum, Porphyridium and Dunaliella could utilise the bicarbonate present in the medium. Data for the other species were inconclusive although the pH dependence of K 1/2CO2 for photosynthesis by Oscillatoria indicated that this species too could utilise bicarbonate. Such observations could, however, not be used as evidence that, at least in the eucaryotic algae examined, bicarbonate was the inorganic carbon species crossing the plasmalemma as Phaeodactylum, Porphyridium and Dunaliella, and Isochrysis all showed the presence of carbonic anhydrase activity in intact cells as well as in crude extracts. 'External' carbonic anhydrase activity represented from 1/4 to 1/2 of the total activity in the cells of these algae. It is concluded that, as a consequence of a CO2-concentrating mechanism, photorespiration was suppressed in the marine microalgae examined although the data obtained did not allow any firm conclusions to be drawn regarding the species of inorganic carbon transported into the cell. Analysis of the age composition of a given species within a community is fundamental to any study of population dynamics and to the subsequent analyses of community interactions such as competition, succession and productivity. A problem exists in that calendar age often provides little information on the role played by any given individual plant within a population. For many populations the most useful definition of population structure is obtained from an analysis of both the functional age and the vitality of the component plants. Data from such studies on populations of marine macroalgae are lacking mainly because of the lack of suitable methods. This paper provides a review of the methods which have ben applied to such analyses in both terrestrial and marine communities, discusses these methods in the context of marine algae and presents the results of a case study on the analysis of population structure in the large brown alga Durvillaea potatorum. Evidence is presented for the occurrence of sexual reproduction including plasmogamy and meiosis, events previously undescribed in the life history of Ascoseira mirabilis. Ascoseira is monoecious. Gametangia are formed in chains within conceptacles. Synaptonemal complexes, structures concerned with chromosome pairing in meiosis, have been observed in the nucleus of gametangial initials. Mature male and female gametes have the same size and appearance, and resemble typical brown algal zoids. Sexual interaction begins after the female gamete settles down, and both zygotes and unfused gametes develop into sporophytes. It is concluded that Ascoseira has the same basic pattern of life history that characterises the order Fucales, and it is argued that this is probably the result of convergent evolution rather than being indicative of close phylogenetic relationship. Life histories are of central importance in understanding evolution and phylogeny of brown algae. Like other hereditary
Copepod faecal pellets and carbon flux in the coastal sea-ice zone
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This dataset contains samples collected at O'Gorman Rocks and Ellis Fjord near Davis station from December 1997 to March 1998. Depth-stratified zooplankton samples were obtained for determination of zooplankton abundance and biomass. Water samples were collected for the determination of chlorophyll a concentration, protist identification and abundance, and the concentration of particulate and dissolved organic carbon. Sediment trap material was collected for the analysis of faecal pellets (identification and CHN analyses), protist identification and abundance, and the measurement of particulate organic carbon concentration. Zooplankton grazing experiments were performed in the laboratory at Davis station and zooplankton were also collected for CHN analyses. Data from this project arose from projects ASAC 963 and ASAC 2229.
Biology and Classification of Macquarie Island Echinoderms
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Metadata record for data from ASAC Project 38 See the link below for public details on this project. From the abstracts of the referenced papers: The origin of echinoderms from Macquarie Island in the Southern Ocean is analysed through a novel application of multivariate statistics. Ordinations are produced from a combination of species distribution, bathymetric, habitat and life history data in order to assess patterns of migration. The analyses distinguish groups of species derived from the Kerguelen Plateau, New Zealand and eastern Antarctica. These groups correlate with attributes expected for epiplanktonic dispersal and range expansion along the North and South Macquarie Ridges respectively. There is no convincing evidence for long-distance pelagic dispersal, migration from the abyssal plain or for human translocation of species. The results indicate that taxonomic groups differ in their ability to disperse, and emphasise the importance of depth in biogeographical analyses. Dispersal by range expansion appears to have been more significant than epiplanktonic dispersal and vicariant rather than long-distance dispersal mechanisms are the preferred explanation for some disjunct distribution patterns. Fifty two echinoderm species are recorded from off Macquarie Island and the Macquarie Ridge in the Southern Ocean. One new asteroid Odontohenricia anarea sp. nov. and one new holothurian Trachythyone nelladana sp. nov. are described. The asteroid genus Calvasterias is synonymised with Anasterias. The asteroids Cycethra macquariensis and Asterina hamiltoni are synonymised with Asterina frigida and placed in the same genus Cycethra. The asteroid Ceramaster lennoxkingi is synonymised with C. patagonicus, Solaster dianae with S. notophrynus, and Anasterias sphoerulatus with A. mawsoni. The asteroids Psilaster charcoti, Odontaster penicillatus, Ceramaster patagonicus, Crossaster multispinus, Solaster notophrynus, Pteraster affinis, Henricia studeri, the ophiuroid Ophioplocus incipiens, and the holothurians Paelopatides ovalis, Synallactes challengeri, Laetmogone sp, Taeniogyrus sp are recorded from the island for the first time. The following species previously recorded from Macquarie Island have been re-identified: the asteroids Odontaster auklandensis (=O. penicillatus), Henricia aucklandiae (=H. studeri), Henricia lukinsi (=H. obesa), Smilasterias irregularis (=S. clarkailsa), Anasterias antarctica (=A. directa), and the ophiuroid Ophiacantha pentagona (=O. vilis). The existence at Macquarie Island of the species Hymenaster sp, Goniocidaris umbraculum and Ocnus calcareus require confirmation. The asteroids Anasterias mawsoni, Pteraster affinis, Porania antarctica and Odonaster meridionalis are reported from the shore around Heard Island. The ecology and relationships of echinoderms from Macquarie Island are discussed.
Biology of the Mertz Glacier Polynya - Protist Data
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Metadata record for data from ASAC Project 1101 See the link below for public details on this project. ---- Public Summary from Project ---- Most of our knowledge of the Antarctic marine ecosystems comes from summer surveys. There are very few observations of this ecosystem in winter and there is a fundamental lack of knowledge of understanding of even basic questions such as 'what is there?' and 'what's it doing?'. The proposed visit to the sea ice zone in winter is a rare opportunity to conduct observations on phytoplankton, krill, birds, seals and whales, so that we can begin to understand the biological processes that go on in winter. Data for this project were intended to be collected on a 1998 winter voyage of the Aurora Australis, but a fire on board meant that the voyage had to return to port before work could be carried out. Data were then collected the following year during a 1999 winter voyage of the Aurora Australis (IDIOTS), which ran from July to September. Data attached to this metadata record, include protist, bacteria and virus data collected from the Mertz Glacier region. The purpose of this research was to quantify and identify the different assemblages of phytoplankton, change in virus populations and the number of live/dead bacteria between Tasmania and the polynya, within the polynya and sea ice. A variety of methods were used including HPLC, light and fluorescent microscopy and the collection of samples for subsequent analysis upon return to the Antarctic Division. More information is available in the download file. The samples were collected by Rick van den Enden.