Organisation at the Ecosystem Level 79
Epilimnion
ermocline
(4° C)
(8° C)
(18° C)
Hypolimnion
0 4° 10°
20°
30°
0 4° 10°
20°
30°
Temperature (°C)
Temperature (°C)
Summer
Spring
(b)
(c)
60
30
60
30
0
0
Depth (m)
(a)
Lake bottom
Lake bottom, sea bed
Lake bottom
Figure 4.8 Temperature layering of a temperate zone’s deep lake. (Modified from
Hadjibiros, K. (2007). Ecology. Ecosystems and Environmental Protection,
3rd edition. Symmetria, Athens (in Greek). With permission.)
500
Nutrients
Euphotic zone
400
300
200
100
Oxygen
Mixed
layer
Depth (m)
Figure 4.9 Oxygen and nutrient profiles in the ocean. Concentration of ambient nutrients and oxygen through the mixed layer are inversely correlated, reflecting
uptake and production by photosynthetic organisms. (From Colinvaux, P.
(1993). Ecology 2. Wiley, New York. With kind permission from John Wiley
& Sons.)