Niger Delta Mangroves: The Nigerian mangrove ecosystem is mostly fragmented deltaic formation located in the River Niger Delta. Occasionally what should have been continuous and uniform mangrove forest in the Delta Islands are interrupted by beach Ridge Island forests sandwiched between the coastal beaches and the estuarine mangrove and island within the mangrove forests. The beach ridge forests typically contain lowland rainforest species. Some have large areas of high quality forests with high concentrations of biodiversity as in Andoni area.
All the major towns and rural mangrove dependent communities such as Abonnema, Bonny, Buguma, Brass, Nembe etc in the Niger Delta area located on such beach ridge forest Islands within the mangrove ecosystem.
The Niger Delta is fringed by a deep belt of mangrove forest, which protects vast areas of freshwater swampland in the Inner Delta. The trees and roots provide rich habitats for a wide range of flora and fauna, much of which is only just beginning to be understood. The dominant feature of the Nigerian coast is the Niger Delta which consists of swampy ground separated by narrow fresh or brackish lagoons (around Lagos) and anastomosing creeks. The network of creeks, separated by muddy deltaic deposits is not stable, since changes in currents and the rate of flow of the river causes erosion of materials already deposited and deposition continues to extend outwards.
These mangroves flank the coastline of western and central Africa, in suitable low energy marine environments. The largest mangrove stand is found in the Niger Delta, which supports the most extensive area of mangrove in Africa. The mangroves of this region have no endemic species but support some endangered species, such as manatees and perhaps pygmy hippopotamuses in the Niger Delta.
Mangroves are important as nursery and feeding areas for marine fishes, and they trap large amounts of sediment. The oil industry, clearance for salt pans, and overcutting by an increasing human population pose serious threats to these mangroves, but some are contained within protected areas.
Climatic conditions are primarily humid and tropicala. In the western part of Nigeria, mangroves are primarily associated with extensive lagoons. These are enclosed part of the year by sediments, when rainfall is lower and freshwater outflow is not sufficient to counteract ocean swells (Sackey et al. 1993). In the remainder of the region, mangroves are primarily associated with river mouths, the largest of which is the Niger River Delta, which may discharge up to 21,800 m3 per second at peak flow in mid-October.
The key factors that influence these mangrove ecosystemsare river floods (Adegbehin 1993) and the tidal range. Tidal range increases from west to east, reaching a maximum of 2.8 m in eastern Nigeria. This allows flood tides to penetrate up to 40–45 km into the interior. The large inputs of freshwater create a low-salinity zone offshore where salinity fluctuations range between 0 and 0.5 percent during the rainy season, and 30 to 35 percent during the dry season.
Coastal mangroves and wetlands are primarily important for large concentrations of birds that use the areas during migration, although some wetland species also breed here. Several of the coastal wetland sites are internationally important for migratory wetland birds.
The mangroves are also important to species found primarily in adjacent habitats, but who may also depend on mangroves for parts of their life cycle. The Niger Delta provides spawning/nursery areas for the fisheries in the Gulf of Guinea. A high diversity is found in the pelagic fish community, with 48 species in 38 families (Ajao 1993).
Estimates of mangrove area provided by Spalding et al. (1997) range between 16,673 and 17,176 km2, of which more than two-thirds are found in Nigeria. Delineations on maps of mangrove areas suggest even larger extents, but estimates are problematic because the mangroves are interspersed with swamp forests.
The most important remaining blocks of habitat are found in the Niger River Delta in Nigeria, to the east of the mouth of the Cross River in Nigeria. The Niger Delta has been growing for millions of years and is still in the process of expanding into the Gulf of Guinea. The delta mangroves mark the transition between swamp forest habitats to pioneer communities on the coast and can extend up to 40–45 km wide (Elijah 2001).
Community struggles in the Nigerian mangroves are directed towards operators of petroleum and allied industries for provision of alternative employment, healthcare facilities, improved rural technologies etc in place of destroyed life-supporting mangrove bases. The struggle manifests as various levels of protests, demands criticisms and occasionally violent demonstration by the aggrieved youths of the Niger Delta areas, particularly oil producing communities. This chapter presents features of the Nigerian mangrove ecosystem, some cases of communal ecosystem deforestation and degradation and measures taken to restore them for the benefit of the rural communities.
Traditionally mangrove swamps are community-owned. Communities rather than individuals held rights to most rural land. Today all land is legally vested on the state government though individuals and communities continue to use the land. The Federal Government owns all mineral rights. This is a source of anger and protests for communities in which oil developments is going on, as the industrial exploitation of natural resources from lands occupied by the rural communities does not appear to benefit such communities and has even led to impoverishment of agricultural soils on which the communities depend for livelihood.
The Nigerian mangrove forests were earlier considered to be the least disturbed of the forest zones of Nigeria. That is not the situation today. In order to develop the Niger Delta areas, canals and road construction have been extensive since 1980. The Nigerian Oil Industry is located mostly in the mangrove forests. The activities of the numerous oil exploration companies have led to fragmentation, deforestation and degradation of the mangrove forest ecosystem. For example Shell Petroleum Development Company alone has shot over 120,000km of seismic lines and created vast degraded bare areas (yet to be estimated) resulting from dredging activities in the mangrove forest. Impacts of other petroleum development companies such as Mobil, Elf, Agip, Chevron on the Nigerian mangroves are yet to be estimated.
– World Widelife / hrmars