Seasonal changes of nutrient concentration in Lake O-ike near Syowa Station, Antarctica

Seasonal variation of nutrients (phosphate, silicate, nitrate, nitrite and ammonium) at various depths of Lake 0-ike near Syowa Station, Antarctica was studied almost every month during the wintering season of 1987 (late March 1987 to mid-January 1988). Although concentrations of nutrients were generally low as in the case of the previous studies, it became clear that nitrate and ammonium increased considerably in the middle and bottom layers during the winter months. These increments may be attributed to degradation of dead planktonic and/or benthic algae and probably escaped observation in the former surveys. Phosphate could not be detected in the present survey, and nitrite was absent in the middle and bottom layers in the winter months

SEASONAL CHANGES OF WATER TEMPERATURE AND CHLOROPHYLL CONCENTRATION IN LAKE O-IKE (Eleventh Symposium on Polar Biology)

Seasonal observations of water temperature and chlorophyll concentration were carried out in Lake 6-ike near Syowa Station, Antarctica, in 1987. Water sampling was begun at the end of March and continued to the next January almost every month. The lake surface was covered with ice during 10 months from March to December. The lake water was cooled through surface from March to August, but the bottom water remained above 3℃ even at the coldest season. According to the results of chlorophyll measurement, the bloom of phytoplankton seemed to occur at two times in April and September mainly at lower layer reaching 0.80 and 1.82mg/m^3, respectively

Biological studies on ecosystems in the Yukidori Valley, Langhovde, East Antarctica

The studies on the mechanism of Antarctic terrestrial ecosystems was planned as a four-year research project from 1986 to 1990 (JARE-27～31) within major projects of JARE. This was undertaken in two different regions of East Antarctica; the coastal ice-free Syowa Station area in Enderby Land and the Sφr Rondane Mountains in Queen Maud Land. The study on ecosystems of the Yukidori Valley, Langhovde, located in the Syowa Station area and approved as Sites of Special Scientific Interest (SSSI) in 1987,was carried out with the following main subjects : 1) observation of biological meteorology to know relationships between vegetation and environmental factors, 2) establishment of small sites or quadrats for a long-term monitoring of vegetational changes and 3) synthetic biological studies on ecosystems along streams and lakes between the coast and the end of ice cap. The study also suits the purposes of the international project "Biological Investigations of Terrestrial Antarctic Systems (BIOTAS)". The present report is to summarize and introduce the general accounts of the biological activities in the Yukidori Valley program