120
The Migrant Biota
0
20
40
17.0
60
)
80
100
~
E
200
:5 0.. CI> 400
0
600 ~14.0
800
1000
1200
1400
J
F
M
A
M
J
J
A
S
0
N
0
Fig.33. Seasonal temperature changes in water column of Levant Basin (courtesy Oren)
results, aeeording to Oren, in the impossibility of enrichment ofthe surfaee waters
by nutrieilts from the bottom layer.
Of all the marine water bodies of the globe the Mediterranean is known to
have the lowest values of nutrient eoneentrations and of primary produetion. The
mean value of total phosphorus in the Levant basin is about 0.8 J.1g/l, showing
only oeeasional peaks. The values of nitrate nitrogen along the Israel shore fluetuate between 0 in the winter to 0.6 J.1gjl during the summer. Near Cyprus, Oren
(1966) measured N0 3 values at the surfaee of less than 1 J.1gjl. According to Oren
these values are eomparable to those in the Western Mediterranean.
However, the differenees are eonsiderable in the values of primary produetion.
The mean gross yearly production of the eoastal waters of Israel is given as
36 mgCjm 2 /year (Oren, unpublished data) which aeeording to this author is some
50-60% less than the annual produetion in the Western Mediterranean. Generally, if values for a eertain depth are eompared, the values in the Levant Basin are
an order of magnitude lower than those of the Western Mediterranean. The
Levant Basin fares better ifthe whole produetive water eolumn is eompared, sinee
the eompensation depth in the Levant is deeper (about 75 m) and the nutrient
supply of the deeper water layers is better than in the West. Again, however,
following the fate of the Lessepsian migrants in the Levant Basin, we eonfme
ourselves to the upper 60-70 m ofthe water eolumn.
Thus the Levant Basin is a subtropical~ saline "eul de sae" of the warmtemperate Atlanto-Mediterranean zoogeographie area, additionally eharaeterized by the lowest values of primary produetion recorded in oeeanie water. The
The Migrant Biota
0
20
40
17.0
60
)
80
100
~
E
200
:5 0.. CI> 400
0
600 ~14.0
800
1000
1200
1400
J
F
M
A
M
J
J
A
S
0
N
0
Fig.33. Seasonal temperature changes in water column of Levant Basin (courtesy Oren)
results, aeeording to Oren, in the impossibility of enrichment ofthe surfaee waters
by nutrieilts from the bottom layer.
Of all the marine water bodies of the globe the Mediterranean is known to
have the lowest values of nutrient eoneentrations and of primary produetion. The
mean value of total phosphorus in the Levant basin is about 0.8 J.1g/l, showing
only oeeasional peaks. The values of nitrate nitrogen along the Israel shore fluetuate between 0 in the winter to 0.6 J.1gjl during the summer. Near Cyprus, Oren
(1966) measured N0 3 values at the surfaee of less than 1 J.1gjl. According to Oren
these values are eomparable to those in the Western Mediterranean.
However, the differenees are eonsiderable in the values of primary produetion.
The mean gross yearly production of the eoastal waters of Israel is given as
36 mgCjm 2 /year (Oren, unpublished data) which aeeording to this author is some
50-60% less than the annual produetion in the Western Mediterranean. Generally, if values for a eertain depth are eompared, the values in the Levant Basin are
an order of magnitude lower than those of the Western Mediterranean. The
Levant Basin fares better ifthe whole produetive water eolumn is eompared, sinee
the eompensation depth in the Levant is deeper (about 75 m) and the nutrient
supply of the deeper water layers is better than in the West. Again, however,
following the fate of the Lessepsian migrants in the Levant Basin, we eonfme
ourselves to the upper 60-70 m ofthe water eolumn.
Thus the Levant Basin is a subtropical~ saline "eul de sae" of the warmtemperate Atlanto-Mediterranean zoogeographie area, additionally eharaeterized by the lowest values of primary produetion recorded in oeeanie water. The