NITRATE (/tg atom/L) 

 5 10 



SILICATE (fig atom/L) 

 7 13 19 25 



9 P 



70 80 90 



TRANSPARENCY (%) 

 17 15 13 



TEMPERATURE (°C) 



100 



70 80 90 



TRANSPARENCY (%) 

 16 14 12 10 



TEMPERATURE (°C) 

 nd temperature records (left) 



SEA SURFACE 

 



Simultaneous nitrate, water transparency, 



show abrupt changes at the same depth. At this level and above, the low 



transparency water has a decreased nutrient concentration, since the 



nitrate has been used up by plankton. A similar abrupt change may be 



observed in the water transparency, temperature, and silicate relationship 



(right). 



F 30'- 



DEPTH OF 

 NITRATE SAMPLING 



^ Vi5°: 



60' — 

 1810 



13° 



12° 



ia^S 



TIME 



1930 



Nitrate values rise and fall in direct relation to the oscillation of an internal wave (in 

 the thermocline). Whenever the thermocline barrier is raised to or near the surface by 

 upweliing or large internal waves, the deeper, colder water, which contains a higher 

 concentration of nitrate, may induce plankton blooms to occur. The nitrate values (right) 

 were recorded at 30 feet simultaneously with temperature (left). 



73 



