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Table 5.1: Distribution of literature on mangroves of Tanzania in various categories.
Category Number of items
International refereed journals 32 24
Published conference proceedings 23 17
Special reports UNEP and UNESCO series and technical reports e.g. management plans, Frontier
series etc. 37 28
Books or book chapters 5 4
Unpublished reports 25 19
Ph.D. theses 5 4
M.Sc. theses 6 5
Total 133
In total there are 5 Ph.D. and 6 M.Sc. theses written on the mangroves. Four of the M.Sc. theses i.e. by Masawe, Nasser, Germanis, and Mkomwa, are not to be found in the University Libraries in the country and hence are
inaccessible to readers in the country. Therefore because of the inaccessibility of information, the literature listed may have been seriously under estimated.
5.4.5 Age of information oldrecent
Majority of the information is quite recent as 20 is from the 80s, 65 is from the 90s to present. Among the oldest published literatures are those of Graham 1929, Grant 1938 and Walter and Steiner 1938. From the
beginning of the 1900 to 1960s only 13 publications could be found that is only 10 of the total. Most of the old literature was written by foreign scientists and mostly based on short duration studies except that of mangrove
planting Grant 1938. On the other hand majority of the recent publications are produced by Tanzanian scientists or in collaboration with foreign scientists.
5.5 Main findingsobservations
5.5.1 Taxonomy, morphology and adaptations
Nine true mangrove tree species are found in Tanzania Table 2 and out of these, Avicennia marina, Rhizophora mucronata
and Ceriops tagal cover larger areas but Xylocarpus mulleccensis is very rare Shunula and Whittick 1996, Semesi, 1991b, 1998. Other plants that are common in mangroves but usually referred to as mangrove associates
Tomlinson 1986 are Acrostichum aureum a fern, Barrigtonia racemosa, Pemphis acidula, Hibiscus tiliaceus, Derris trifoliata, Thepseia populnea,
and Phoenix reclinata a palm. Some taxonomic treatment of mangrove trees of Tanzania can be found in Williams 1949, Shunula and Whittick
1996 and Semesi 1991b-l but the best taxonomic work of the mangrove trees of Tanzania which also include those of other countries in eastern Africa is described in a series of publications on Flora of Tropical East Africa. The
Taxonomy of Rhizophora mucronata, Ceriops tagal and Bruguiera gymnorrihza all belonging to the family Rhizophoraceae are described by Turrill and Milne-Redhead 1956. Verdcourt 1992 described Avicennia marina
family Verbenaceae and Styles and White 1991 described Xylocarpus granatum and Xylocarpus mulleccensis family Meliaceae. Sonneratia alba family Sonneratiaceae has been described by Williams Sangai 1968 and that of
Lumnitzera racemosa
, family Combretaceae by Wickens 1973. Copies of these publications are found in the Herbarium of the Botany Department, University of Dar es Salaam. Shunula and Whittick 1996 and Semesi 1991b-
l, 1997 provide illustrated shorter descriptions of the mangrove trees useful for rapid field identification. They used morphological characteristics of leaves, flowers, propagules, roots, etc. in classifying the species.
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Mangrove plants share a number of specialised adaptations allowing them to cope with regular flooding of roots and sediments by salty waters. As an adaptation to anaerobic condition trees have developed exposed breathing
roots Walter and Steiner 1936, McCusker 1971 that absorb oxygen from the air at low tide. Avicennia marina and Sonneratia alba
for example have pneumatophores peg roots, Bruguiera gymnorrhiza and Ceriops tagal have knee roots but Rhizophora mucronata have prop roots that grow from the trunk and lower branches Walter and Steiner
1936, McCusker 1971, Semesi 1991, 1997, Shunula and Whittick 1996. Mangroves cope with shallow unstable soils by having shallow widespread root systems, with support structure of buttresses and with above ground roots
which do an excellent job of holding them upright. These root systems retard water flow, which leads to a number of environmental services. The quiet environment not only encourages sediment to settle but also inhibits their
resuspension Julius 1992. Mangroves thus stabilise shorelines, and reduce flood damage by dissipating the energy of floodwaters. Some other adaptation characteristics include; low water potentials and high intercellular
salt concentration to maintain favourable water relations in saline environment, foliage salt-excretion to remove excesses salt from sap, Xerophytic water conserving leaves to cope with periods of high salinity stress and
buoyant, viviparous propagules to promote dispersal and establishment of new and existing stand.
Table 5.2: Mangrove tree species, their local names and direct uses in Tanzania
Mangrove Tree Species Scientific name Local name
Uses
Avicennia marina Family
Verbenaceae Mchu
Inferior firewood, but used for boiling of brine, fish smoking and production of lime, building dugout canoes
and beehives; drums, carts, leaves used as goat and cattle fodder; branches support beehives, construction of beds
Bruguiera gymnorrhiza
Family: Rhizophoraceae
Msinzi or muia
Good firewood; used for fish smoking, fishing stakes; poles for building, telephone poles.
Ceriops tagal Family:
Rhizophoraceae Mkandaa
Good firewood; poles; drying fish, fishing stakes; fence posts, poles for house building, timber for boat building,
children use fruits to make whistle Heritiera littoralis
Family: Sterculiaceae
Msikundazi or mkungu
Good firewood; timber for boat-building; furniture; dhow masts
Lumnitzera racemosa
Family: Combretaceae
Kikandaa or mkandaa
dume Good firewood, charcoal and building poles
Rhizophora mucronata
Family: Rhizophoraceae
Mkoko Good firewood; charcoal, poles for building; fence posts;
fish traps; fishing stakes, barks used for dying nets
Sonneratia alba Family:
Sonneratiaceae Mililana
Good firewood; commonly used in boat-building; pneumatophores used as fish net floats
Xylocarpus granatum
Family: Meliaceae
Mkomafi Good firewood; used for fish smoking; boat-building;
making furniture. The seeds are used to treat stomach problems and the fruit pulp to cure rashes fruit also used
to induce abortion high dosages are said to be lethal
Xylocarpus molluccensis
Family: Meliaceae
Good firewood
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5.5.2 Reproduction and growth
