Agulhas Bank Plankton
209
Its concentrations are usually smaller than those of other swarming species. Two other
species, Euphausia recurva and E. lucens, were found swarming over the edge of the Bank
on isolated occasions only (Fig. 8 a - d). The limits of temperature, salinity and dissolved
0
0
Euphausia recurva
33°5 0
1964 - 1966
0
0
0
0
34°
0
0
0
0
0
0
35°
0
0
0
0
0
0
0
0
0
0
36°5
0
©
0
0
0
17"E
19°
0
21°E
Fig. 8 c
• Euphausia sim ilis
•
t:. Euphausia spinifero
33°5
•
• Thysanoessa gregoria
o Nemaloscelis megalops
1964 - 1966
34°
4J
If>
•
35°
•
0
•
t:.
t:.
t:.
36°5 @
0
•
17°E
19°
21°E
Fig. 8 d
O2 content within which swarming was observed in 6 species are plotted in Fig. 9. The
species swarming over the Bank are those which show the widest tolerance for the three
environmental factors considered.
The biomass of euphausiids in comparison with the west coast, is low over the Bank.
In winter 1965, the volume of euphausiids ranged from 0.0002 to 0.03 ml m-3, in summer
from 0.001 to 0.02 ml m- 3 • Off the west coast in the same periods the figures were 0.0001
to 0.26 and 0.0001 to 0.06 respectively.