A Brief Note on Diatom Flora of Antarctic Inland Waters

We examined diatom flora of Kasumi Rock and Shinnan Rocks around Syowa Station, and found that Kasumi Rock had 31 species of diatoms including 14 endemic species, and Shinnan Rocks had 32 species of diatoms including 6 endemic species. Comparing with total number of species, the number of endemic ones was rather small. On the other hand, at Cape Royds near McMurdo Station, the total number of species was 21,including 13 endmic species. At Cape Evans, the total number of species was 15,including 9 endemic species. At Cape Barne, the total number was 11,including 9 endemic species, and near McMurdo Station the total number was 16,including 10 endemic species. Although the total number of species around McMurdo Station is small, the rate of endemic species is much higher. Dominant species near Syowa Station were Hantzschia amphioxys, Navicula cryptocephala, Nitzschia palea and Tropidoneis leavissima, and cosmopolitan species were more but endemic species were less. Around McMurdo Station, dominant species were Tropidoneis laevissima, Pinnularia cymatopleura, Navicula muticopsis and Navicula peraustralis, but these were all endemic species and there were no cosmopolitan species. These facts indicate that around Syowa Station, cosmopolitan species were more numerous than endemic species and there was not so Antarctic vegetation, but that around McMurdo Station located in latitude 80°S, which is 10°higher than Syowa Station almost all species were endemic species and few cosmopolitan species were found and there was almost completely Antarctic vegetation. We found that the difference of only 10°in latitude causes such remarkable variation of diatom flora

Ice Flora (Bottom Type): A Mechanism of Primary Production in Polar Seas and the Growth of Diatoms in Sea Ice

A yellowish-brown layer at the bottom of summer sea ice, upturned by an icebreaker, off the coast at Point Barrow, Alaska, extended up to 30 cm from the bottom. It consisted of large diatom colonies which were found to have been formed in brine included in fissures between vertically oriented ice crystals. Grazing by zooplankton was highly restricted because the structure of the ice microhabitat prevented their entry. The chlorophyll content of the layer studied was 100 times greater than that of sea water under the ice. This suggests that the most important primary production of the Arctic is in the sea ice. The biological environment of the colored layer at the bottom of the sea ice is summarized, viz: relatively stable temperature (-3 to 0 C), sufficient nutrient supply, variable osmotic pressure, stronger light conditions than in sea water below, limited grazing by zooplankton, and probable abundance of organic matter.Flore de la glace (type basal) : mécanisme de production première dans les mers polaires et croissance des diatomées dans la glace de mer. Durant l'été de 1964, une étude effectuée au large de Barrow a révélé que, dans l'Arctique, la glace de mer présente une structure stratifiée par la croissance de diatomées. Ces diatomées se multiplient dans les solutions salines des microfissures entre les fins cristaux de la glace et forment une couche brune près de la surface inférieure.Le contenu chlorophyllien de la couche étudiée était de 120 µg par litre, c'est-à-dire cent fois plus grand que celui de l'eau de mer sous la glace, ce qui permet d'émettre l'hypothèse que, dans l'Arctique, la production première se fait dans la glace de mer, surtout au printemps et au début de l'été. Des études ont aussi été menées sur la flore des diatomées et le mécanisme de dégradation de la glace lié aux effets biologiques; on a finalement comparé les conditions arctiques et antarctiques

ナンキョク タイリク カスミイワ ロガン チタイ ノ ケイソウ ショクセイ

The Kasumi Rock Ice-Free Area is located at 68°21\u275"1.S. and 42°15\u2713"1.E. This area seems to have experienced not so many years since the glacial epoch, as no evidence of weathering nor weathered rocks were found there. Moss and lichen were not seen either. Only moraines were found in some places. 30 algae samples from 8 ponds were collected in polyethylene bottles. The time available for detailed investigation of the environmental factors was too short. The result is outlined in Table 1. The investigated ponds are 10-100 meters in diameter and less than 60cm in depth. The contents of nutritious salts (P, NH_3, N0_2) in these ponds are so small that a quantitative analysis was impossible, just like the case of the Shin-nan Rock Area. The SiO_2 content was 19-20 mg/l (standard). Ponds in the Kasumi Rock Area can be classified into two groups, one is of fresh water ponds and the other is of brackish water ponds. The former includes Stations 1 and 8, and the other has 5 stations (Stations 2-7). Concerning PH, the former was a little acidic and the latter was alkaline. The Kasumi Rock fresh water ponds contain much more Chlor ion than those of the Shin-nan Rock Area. Station 1 has 358 mg/l Chlor ion. In the brackish water ponds, the Chlor ion content varies with pond, and ranges from 4,959 to 9,523 mg/l. This is ca. 1/2-1/4 of Chlor ion in sea water. Almost all these brackish water ponds contain hydrogen sulfide and have a smell. Their bottom mud is black. In the ponds of the Kasumi Rock Area, blue-green algae and diatoms are predominant, whereas in the Shin-nan Rock Area only blue-green algae are found. The algal vegetation at Kasumi Rock is characterized by diatoms: Diatoms flora of the fresh water ponds differs from that of the brackish water ponds. The former belongs to the Navicula muticopsis association, and the latter to the Navicula cryptocephala var. intermedia-Navicula cryptocephala-Tropidoneis laevissima association. The writer found 46 taxon of diatoms in these ponds. Among 34 taxon already identified, 24 taxon were salt water species. The rest 12 taxon have not yet been identified. Station 1 (Fresh water pond). 6 samples: Navicula muticopsis and 6 other taxon. Navicula muticopsis association. Station 2 (Brackish water pond). 6 samples: Navicula cryptocephala var. intermedia and 16 other taxon. Navicula cryptocephala var. intermedia association. Station 3 (Brackish water pond). 2 samples: Navicula cryptocephala var. intermedia, N. cryptocephala, Tropidoneis laevissima and 16 other taxon. Navicula cryptocephala var. intermedia -N. cryptocephala- Tropidoneis laevissima association. Station 4 (Brackish water pond). 2 samples: Navicula cryptocephala, N. c. var. intermedia, and 4 other taxon. Navicula cryptocephala-N. c. var. intermedia association. Station 5 (Brackish water pond). 2 samples: Navicula cryptocephala var. intermedia and 15 other taxon. Navicula cryptocephala var. intermedia association. Station 6 (Brackish water pond). 2 samples: Navicula cryptocephala var. intermedia, Tropidoneis laevissima and 8 other taxon. Navicula cryptocephala var. intermedia-Tropidoneis laevissima association. Station 7 (Brackish water pond). 9 samples: Tropidoneis laevissima, Navicula cryptocephala var. intermedia, Navicula cryptocephala and 28 other taxon. Tropidoneis laevissima-Navicula cryptocephala var. intermedia-Navicula cryptocephala association. Station 8 (Fresh water pond). 1 sample: Navicula muticopsis and 2 other taxon. Comparing the diatom from the Shin-nan Rock Ice-Free Area with those from the Kasumi Rock Ice-Feee Area, it is known that the kinds and the number of individuals are less in the former area. The writer found that the latter area had many more salt water diatoms than in the former, probably due to the brackish pond existing there