TILSETH and ELLERTSEN: FOOD ORGANISMS OF LARVAL COD 



Austnesfjorden Hella 27 - 28 Apr. 81 

 A 0420 



2 n. miles 



21 30 H 



Austnesfjorden Hella 27 -28 Apr. 81 



2 n. mile s 



21 JU H 



FIGURE 7.— Particle (A) and nauplii (B) distributions (per liter) in the upper 40 m of Austnesfjord, 27-28 April 1981, at 21.30 to 0420 h. 



(Particle size range 150-600 (im, nauplii all sizes.) 



one patch with >50 particles/nauplii per 1 was ob- 

 served between 20 and 40 m at the bottom of the 

 fjord. 



Effect of wind driven turbulence on vertically 

 migrating particles is presented in Figure 9A, B, and 

 C. The figure presents data collected continuously 

 from 9 to 15 May 1980, on wind velocity and direc- 

 tion, temperature, and particle distribution in the 

 water column. Due to technical problems, only par- 

 ticles within the size range 300-500 ju.m were 

 measured by the particle counter in 1980. From 9 to 

 12 May the wind was blowing downfjord with varying 

 velocity. On 1 2 May the wind changed direction 180° 

 and blew upfjord with a velocity of 5- 1 m/s (Fig. 9A). 

 Unfortunately, observations of temperature and par- 

 ticle distribution were not made from 10 to 11 May. 

 However, one 24-h station was made on 9 May during 

 the period when the wind was blowing downfjord. At 

 this time, the upper 10 m of the water column showed 

 tendencies of mixing, and colder intermediate water 



masses were observed from 15 to 55 m above the 

 transition layer. Within the cold intermediate water 

 masses a particle maximum layer was found (Fig. 

 9C). It is believed that the wind was blowing the sur- 

 face water downfjord and this was compensated for 

 by intermediate water masses moving in the opposite 

 direction. On 9 May we observed a patch of particle- 

 rich intermediate water moving in from the outer part 

 of the fjord. The particle isolines in the upper 10 m 

 followed the isotherms (Fig. 9B, C). When the wind 

 direction reversed and increased in velocity on 12 

 May (Fig. 9A), the fjord became more exposed to the 

 wind force and the wave action from the open ocean 

 outside the fjord. Under this condition the current 

 system will reverse (Furnes and Sundby 1981). The 

 surface water became completely mixed within about 

 24 h (Fig 9B), and no particle diel vertical migration 

 was observed during this condition (Fig. 9C). The 

 particle concentration decreased and became almost 

 homogeneous from the surface to 40 m. 



147 



