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resulted in a decline in local fish catch inside the mangroves. This negative change
was reinforced by the increased number of local fishermen. A decrease in the population of silurid, tilapia, mullets, shrimp, oyster and crab species, was probably related
to changes (siltation, reduced water circulation, etc.) that occurred in the waterways.
Crab assemblage has shown a considerable variation in terms of species richness
and abundance according to deforestation (Ngo-Massou et al. 2016). Abundances of
Chiromantes buettikoferi De Man, 1883 (from 4.5 to 2.6% of individuals), Metagrapsus
curvatus Herklots, 1951 (from 12 to 7.68% of indiviuals), Sesarma sp. (from 4.3 to
2.7% of individuals), C. angolense Brito Capello, 1864 (from 10.73 to 3.30% of specimens) and Perisesarma alberti Herklots, 1951 (from 16.61 to 6.42% of specimens)
decreased. The number of species in Sesarmid crabs (from 10 to 8 species) and
Gecarcinid crabs (from 3 to 1 species) fallen down. The importance of vegetation and
channel distance on crab distribution has been described (Ngo- Massou et al. 2014).
Vegetation is highly dominated by Rhizophora plant and that zone is the most diversified (18 crab species) which, two crab Helice sp. and Maja squinado Herbst, 1788
were strictly pledged. Therefore, the overexploitation of Rhizophora spp. lead the loss
of these two indigenous crabs. Furthermore, Cardisoma spp. and Uca tangeri Eydoux,
1835 species are the most terrestrial crabs, because they live essentially close to back
mangroves. With regards to anthropogenic activities, these terrestrial crabs are mainly
threatened more than Callinectes pallidus Rochebrune, 1883 and Portunus validus
Herklots, 1951, crabs found only near channels (marine crabs).
3.6 Conclusion
In spite of the existing laws and regulations in order to protect mangrove ecosystems in Cameroon, the rate of deforestation is significantly high in Douala periurban mangroves. The depletion issue from natural disaster must be considered as
negligible in compare with anthropogenic activities. The fact that state projects
toward mangrove areas did not especially show example of the importance of biodiversity protection, neighboring population profited from the authorities’ laxity to
accelerate the depletion mainly by building up to the channels and tributaries.
Considering in addition the demographic pressure in the city, always coupled
with human poverty and associated here with a high level of incivism, the mangrove
ecosystem will disappear in less than two decades if the authorities continued to
mismanage the population settlement in coastal peri-urban areas.
References
Abata T (1994) La mangrove de l’estuaire du Wouri (Douala-Cameroun). Etude de la microtopographie et caractérisation morphologique et biochimique des sols. Dissertation, the University of
Yaounde I, Cameroon
Abuodha PAW, Kairo JG (2001) Human-induced stresses on mangrove swamps along the Kenyan
coast. Hydrobiologia 458:255–265
N. Din et al.
resulted in a decline in local fish catch inside the mangroves. This negative change
was reinforced by the increased number of local fishermen. A decrease in the population of silurid, tilapia, mullets, shrimp, oyster and crab species, was probably related
to changes (siltation, reduced water circulation, etc.) that occurred in the waterways.
Crab assemblage has shown a considerable variation in terms of species richness
and abundance according to deforestation (Ngo-Massou et al. 2016). Abundances of
Chiromantes buettikoferi De Man, 1883 (from 4.5 to 2.6% of individuals), Metagrapsus
curvatus Herklots, 1951 (from 12 to 7.68% of indiviuals), Sesarma sp. (from 4.3 to
2.7% of individuals), C. angolense Brito Capello, 1864 (from 10.73 to 3.30% of specimens) and Perisesarma alberti Herklots, 1951 (from 16.61 to 6.42% of specimens)
decreased. The number of species in Sesarmid crabs (from 10 to 8 species) and
Gecarcinid crabs (from 3 to 1 species) fallen down. The importance of vegetation and
channel distance on crab distribution has been described (Ngo- Massou et al. 2014).
Vegetation is highly dominated by Rhizophora plant and that zone is the most diversified (18 crab species) which, two crab Helice sp. and Maja squinado Herbst, 1788
were strictly pledged. Therefore, the overexploitation of Rhizophora spp. lead the loss
of these two indigenous crabs. Furthermore, Cardisoma spp. and Uca tangeri Eydoux,
1835 species are the most terrestrial crabs, because they live essentially close to back
mangroves. With regards to anthropogenic activities, these terrestrial crabs are mainly
threatened more than Callinectes pallidus Rochebrune, 1883 and Portunus validus
Herklots, 1951, crabs found only near channels (marine crabs).
3.6 Conclusion
In spite of the existing laws and regulations in order to protect mangrove ecosystems in Cameroon, the rate of deforestation is significantly high in Douala periurban mangroves. The depletion issue from natural disaster must be considered as
negligible in compare with anthropogenic activities. The fact that state projects
toward mangrove areas did not especially show example of the importance of biodiversity protection, neighboring population profited from the authorities’ laxity to
accelerate the depletion mainly by building up to the channels and tributaries.
Considering in addition the demographic pressure in the city, always coupled
with human poverty and associated here with a high level of incivism, the mangrove
ecosystem will disappear in less than two decades if the authorities continued to
mismanage the population settlement in coastal peri-urban areas.
References
Abata T (1994) La mangrove de l’estuaire du Wouri (Douala-Cameroun). Etude de la microtopographie et caractérisation morphologique et biochimique des sols. Dissertation, the University of
Yaounde I, Cameroon
Abuodha PAW, Kairo JG (2001) Human-induced stresses on mangrove swamps along the Kenyan
coast. Hydrobiologia 458:255–265
N. Din et al.