The concentration of phytoplankton pigment (Chlorophyll) is assessed indirectly by monitoring its fluorescence in the water. The data show a moderately small amount of phytoplankton at the start of 2009 followed by a steady increase in early February peaking in early March. Phytoplankton declined slowly in April but then declined more rapidly at the end of April and early My. The steep decline between about 24 April and early May coincided with a transient period of temperature stratification.

There is a ‘chain’ of thermistors recording temperature within the lake at approximately every meter. For clarity, only thermistors at 0.1, 6, 9 and 15 m are plotted here. At the start of the year temperatures were either uniform with depth or there was an ‘inverse’ stratification with surface waters cooler then 4oC floating on warmer water below. ‘Normal’ stratification (warmer surface water) started to form on several occasions in March and April but broke down as a result of wind and cold weather. The lake is almost completely mixed in Mid May at the end of this data series.