biological diversity and tropical forests in tunisia - PART

Urban wastes (sewage) also alter coastal ecosystems. Virtually all of
the major cities discharge at least some untreated sewage into the sea, as
well as large quantities of partially treated wastewater. Runoff from
agricultural lands carries chemical compounds such as nitrogen fertilizers
and over 35 types of pesticides, including: Malathion, Dieldrine, Lindane
and 2.4-D (~ndren and Salem 1978). Chemical compounds affect the marine
flora and fauna and some can be passed on the the birds, 'wild mammals and
people that eat seafood.
In addition to chemical pollution, coastal areas are eensitive to:
3.1 .1 . Coral Coast
Shoreline development
Shoreline degradation:
- Erosion due to grazing, vegetation removal, soil
disruption
- Coral harvesting
The corth coast from Tabarka to Bizerte is also known as the "Coral
Coast". The Kroumirie/~ogod mountain ranges give the coastline its
characteristic steep slopes, low cliffs and rocky shores, interspersed
with sandy beaches and coastal plaics. Even where the mouctaic edges are
under the sea, the slopes remain fairly steep. The depth is greater than
100 m within 10 km of the shore along almost the entire coast. The
continental shelf is narrow, often with a rough steep slope and cut with
deep channels (~zouz 1975).
The Mediterranean sea moderates the ambient temperatures of the coast.
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Near Tabarka the average annual temperature is at the 16 C isotherm.
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Progressing east, the average annual temperatuge increases to the 17 C
isotherm near Cap Negro, and at Bizerte the 18 C isotherm is reached.
Domicact winds are from the W-NW, bringing moist air in from the sea.
Annual precipitation decreases from a rate of > 900 mm annually to 600 mm
annually as one progresses eastward along the Coral Coast. Precipitation
patterns appear to be related more to the presence of the mountain ranges
than to coastal icfluences.
A. Vegetation
Coastal vegetation types reflect those of the inland forests, but
trees are often stunted, resulting in vast coastal maquis. Salt
intolerant species, such as aleppo pine Pinus halepensis, are replaced by
more tolerant species; however, there is a sizable aleppo pine forest at
Ras el Korac, aboat 15 km west of Bizerte.