2IO DISCOVERY REPORTS 



almost certain that the optimum Hght zone must He much closer to the surface inshore. 

 It may be noted that although the two net hauls can give no detailed idea of the dis- 

 tribution with depth, at all stations where a comparatively rich phytoplankton was 

 found, nearly all the diatoms appeared to be in the upper 25 m. 



TIDE 



The rise and fall of the tide in King Edward Cove is only 3I ft., so that it was not 

 surprising to find that the tide had but little effect on the waters of the deep open bay. 

 On one occasion only the effects of an ebbing spring tide were felt as far out as the 

 routine station position. This was at St. MS 104 when the salinity at the surface was 

 low. The wind on the day of the station was south-east, aiding the ebb over the reef at 

 the mouth of Moranen Fjord, but while on station it suddenly flew round to the north- 

 east and blew freshly for half an hour. A steep chop immediately got up, which, under- 

 run by the northerly swell rendered work very difficult. In general there did not appear 

 to be any correlation between the tide and hydrological and plankton conditions. Wind 

 was the most potent agent in moving the water masses. 



HYDROLOGICAL FACTORS 



The temperature in the upper layers naturally showed considerable fluctuation in 

 relation to wind, sunshine, the presence of glacier ice, and so on. From Fig. 81 it will 

 be seen that there was a gradual rise up to St. MS 99 (February 5), after which the 

 temperatures remained fairly high with no very marked falling off until the end of the 

 season. At the early stations minus temperatures were recorded in the deeper layers 

 which naturally took longer to get warmed. 



The maximum observed at the surface was 2-9° C. at St. MS 97 (January 22) and the 

 minimum o-6o° C. at St. MS 105 (March 19) with much glacier ice about. At the lowest 

 depth worked, 75 m., the maximum was 1-55° C. at St. MS 104 (March 12) and the 

 minimum, — o-88° C, at the first full station worked. At this station the mean for the 

 whole column (Fig. 84) was also at its lowest, — o-io° C, the maximum, i-86° C, being 

 reached at St. MS 99 (February 5). It is to be noted that the means for the whole 

 column (Fig. 84), 75-0 m., give a better idea of the falling off towards the extreme 

 end of the season than the more variable means for the surface layers (Fig. 81). 



The general nature of the temperature curve, together with the scanty phytoplankton, 

 indicates that temperature is the main factor in determining the oxygen content of the 

 water in the bay (Fig. 84). The initial value was high with supersaturation at the surface 

 during the first diatom maximum, otherwise the temperature appeared to regulate the 

 amount of oxygen very closely. The peak in the oxygen curve at St. MS 97 should not 

 be considered as due to the activity of the comparatively rich phytoplankton of the week 

 before, as the water of the upper layers was of quite different origin at the two stations. 

 It seems highly probable that this is to be explained by the influence of water driven out 

 of Moranen Fjord by the south-easterly winds preceding that station. The surface water 



