PANGANI BASIN WATER BOARD

and Coastal forests. At least four mammal
species, five bird species, four amphibian
species, twenty seven reptiles, forty
butterflies, twenty millipedes, four hundred
plants and an unknown number of flies,
beetles and other invertebrates are endemic
to East African coastal forests (Burgess
et al., 1996). This level of endemism has
arisen because of the forests’ isolation from
other African forests, their old age and the
fact that the Indian Ocean’s climate has
remained more or less stable over very long
periods of time.
As a result, the threats that many of these
species face relate to the preservation
of their environment. Because so much
of the Eastern Arc and Coastal Forest is
threatened, many of their animal species
are considered endangered (see box 9).
On Mt. Kilimanjaro, 2,500 species of plants
have been recorded, including 130 tree species
from 100 genera and 50 families. 170
shrub species have been identified from the
mountain’s forests, and these belong to over
100 genera and 40 families (Lambrechts et
al. 2002). Some 140 mammal species are
recorded from the mountain, including the
world’s largest known population of Abbot’s
duiker, a globally threatened species (Lambrechts
et al., 2002). The park contains an
endemic shrew, four endemic species and
subspecies of butterfly, six endemic plants,
twelve endemic mosses and liverworts
(Baker and Baker, 2001).
Box 8: Biodiversity hotspots
Biodiversity hotspots are designated by the American
conservation organisation, Conservation International.
They are regions of the globe that harbour a great
diversity of species but which, at the same time, have
been significantly impacted and altered by human
activities. Plant diversity is the basis for hotspot
designation, because plants are the foundation for
diversity in other taxonomic groups. In order to qualify,
a site must contain at least 1,500 endemic plant
species, fully 0.5% of the global total of known plants.
In addition, 70% or more of the site’s original habitat
must have been destroyed or altered.
Between them, the world’s 25 biodiversity hotspots
cover just 1.4% of the globe’s area, but contain 44%
of the world’s known plants, and 35% of all known
terrestrial vertebrates.
Such hotspots are often ‘islands’ of biodiversity
surrounded by areas of relatively poor biodiversity.
As is the case with the Eastern Arc Mountains, these
areas have typically obtained their biodiversity as
a result of environmental conditions that have not
changed over great lengths of time.
Besides the Eastern Arc and Coastal Forests
Biodiversity Hotspots, there are four other hotspots
in Africa: the Madagascar and the Indian Ocean
Islands, the Guinean Forests of West Africa, the
Cape Floristic Region and the Succulent Karoo
along Africa’s south-western coast.
Source: www.biodiversityhotspots.org.
A rare and endangered bull shark
(Carcharrhinus leucas) occasionally swims
up the Pangani River from its delta, and has been seen as far up its course as Jambe (TANESCO,
1994). Besides the shark, however, none of the river’s 41 species of fish are thought to be endangered.
It does contain several endemics, comprising two cyprinids (Barbus paegnstecheri and Labeo coubie),
one characin (Rhabdalestes leleupi) and three cichlids (Ctenochromis pectoralis, Oreochromis korogwe
and O. pangani) (TANESCO, 1994).
The tilapia genus, Oreochromis, derives its name from the Latin for ‘mountain chromis’, which Gunther
gave it in 1889 after discovering Oreochromis hunterti in Lake Chala, on the slopes of Mt. Kilimanjaro
(Dadzie et al., 1988). In Lake Jipe, an additional two endemic tilapia are to be found: Tilapia jipe and
T. girigan. Oreochromis esculentus, a Lake Victoria endemic 4 , has been introduced to the basin and
comprises a substantial part of the catch in Nyumba ya Mungu Reservoir. An additional exotic, T. rendalii,
has been collected from Lake Chala.
I4
n a curious twist of fate, this species is now extinct from Lake Victoria.
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