In Nun River forest reserve of Bayelsa state, Hamadina et al. The authors further reported the wildlife resources to comprise of 27 species of mammals, 34 species of reptiles and 10 species of amphibians using quantitative and qualitative approach.
In Delta state, Lameed 63 reported the presence of 47, 7, and 3 species of mammals, reptiles and amphibians in Kwale forest reserve and Okpai ecosystem. Furthermore, Lameed 63 also reported that due to movement nature of birds, at different locations of the ecosystem varying species were found including 19 species in villages and farmlands, 49 species in forest area and 14 species around river bank and beaches.
Insects is another diversity that play essential ecological roles. Okore et al. Like birds, their distribution and occurrence frequency shows high dissimilarity depending on the region and prevailing human activities of an area.
In different locations in the Niger Delta, several plant species have been reported. For instance, Ubom 66 reported the presence of plant species which are distributed into 88 families in some areas within the Niger Delta region.
In different locations, several plant species have been reported. Eludoyin et al. Uzodimma 68 also reported the presence of 72 plant species used by the indigenous people of Ogii in Okigwe, Imo State for the treatment of different type of ailments. Wetlands play essential ecological, social and economic roles. In the Niger Delta, the wetland resources is essential because it is a source of fuel wood, timbers etc used for art and construction works, breeding ground for several wildlife, nestling arena for migratory birds, spawning place for different fish species, and source of plants with insecticidal and antimicrobial properties.
Some of the biodiversity including plants and animal has some medicinal uses. This is because fats, oil, skin of some animals are used in treating some certain diseases in human in addition to their food purposes. For instance, Costa-Neto 71 which stated that the tusks of hippo Hippopotamus amphibious can be used for aphrodisiacs and ornamentals, and the fat extracted from manatee Trichechus senegalensis can be used to cure rheumatism, boils, and backache.
Costa-Neto 71 also reported that the blood of the black caiman Melanosuchus niger can used to treat epilepsy and stroke; ants of the genus Pseudomyrmex can be used for the treatment of toothache and reliving painful joints pains; the various anatomical parts of the rattlesnake Crotalus sp.
Different parts of animal are used in traditional medicine. Some of the animals mentioned by Costa-Neto 71 have been previously reported in the Niger Delta region. However, most of them have not been sighted in the region within the last 20 decades. Several plants found in Niger Delta region have been widely reported to have medicinal purposes.
Some of the plants mentioned by the authors are found in the Niger Delta region. Several plants have been reported to have antimicrobial effects including Musanga cecropioide , 74 Vitex grandifolia , 75 Alstonia boonei , 76 Alchornea cordifolia , 77 and many other species of plants.
Some of this plants species have emerged as credible source for synthesis of new medicine. Several part of mangrove plant is used as poles communication lines, foundation piles, local sign posts, the saplings and twigs mud and thatch house construction. The forest acts as a shield for soils beneath, especially from effects of natural factors such as heavy rainfall, high temperatures and destructive winds and erosion. Urbanization, industrialization, intense agricultural practices, deforestation, use of chemical based fertilizers, pesticides, emission from the consumption of fossils fuel are the major factor leading to environmental degradation.
The rate of deforestation is high leading to loss of valuable plants species and animal habitats thereby exposing them to excessive exploitation. Some of the effects of environmental degradation include increased rate and intensity of erosions, flooding, etc. The loss of forest resources through excessive exploitation, illegal poaching, deforestation, uses of chemicals, logging, bush burning is having an impacts on the diversity, composition, abundance of biodiversity in the Niger Delta.
Thereby predisposing majority of species to IUCN criteria such as threatened, endangered, critically endangered and extinction. As such some species have not been seen in the region with the last decades thereby assuming that they have gone on extinction in the region. The decline in the forest is affecting bare ground km 2 , water km 2 , farmlands km 2 , urban area km 2 , mangroves km 2 , freshwater forest km 2 and lowland rainforest km 2.
Due to the importance of medicinal anim als, excessive exploitation could pose danger to traditional health practitioners that use different parts of the aquatic mammals for treatment. Mangroves, lowland rainforest and freshwater forest ecosystems of the Niger Delta which is essential for the survival of several families of plants and animals under intense threat due to human activities in the region.
This is having impact on the biodiversity of the ecosystem, thereby predisposing some species to IUCN classification such as threatened, endangered and extinction. This study showed that lowland rainforest is the major ecosystem being loss. The loss of ecosystem due to human activities is a threat to the ecological role of the Niger Delta forest including protection of shoreline, breeding ground for several migratory birds, spawning group to both shell and fin fish, habitats to several endemic wildlife.
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British Journal of Humanities and Social Sciences. Ogbe MG. The image was taken by the Expedition 41 crew. It has been cropped and enhanced to improve contrast, and lens artifacts have been removed.
The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet.
Caption by M. Image of the Day Land Water. This wetland in the interior of Botswana is an oasis for biodiversity in the midst of the arid Kalahari Desert. The Ebro River Delta, located along the eastern coast of Spain, is one of the largest wetland areas in the western Mediterranean region. Image of the Day Land Life. In the Eocene, the coastline shape became convexly curvilinear, the longshore drift cells switched to divergent, and sedimentation changed to being wave-dominated Reijers and others, At this time, deposition of paralic sediments began in the Niger Delta Basin proper and, as the sediments prograded south, the coastline became progressively more convex seaward.
Today, delta sedimentation is still wave-dominated and longshore drift cells divergent Burke, The Tertiary section of the Niger Delta is divided into three formations, representing prograding depositional facies that are distinguished mostly on the basis of sand-shale ratios. Avbobvo, ; Doust and Omatola, ; Kulke, The Akata Formation at the base of the delta is of marine origin and is composed of thick shale sequences potential source rock , turbidite sand potential reservoirs in deep water , and minor amounts of clay and silt fig.
Beginning in the Paleocene and through the Recent, the Akata Formation formed during lowstands when terrestrial organic matter and clays were transported to deep water areas characterized by low energy conditions and oxygen deficiency Stacher, Little of the formation has been drilled; therefore, only a structural map of the top of the formation is available fig. It is estimated that the formation is up to 7, meters thick Doust and Omatsola, The formation underlies the entire delta, and is typically overpressured.
Turbidity currents likely deposited deep sea fan sands within the upper Akata Formation during development of the delta Burke, Deposition of the overlying Agbada Formation, the major petroleum-bearing unit, began in the Eocene and continues into the Recent fig.
The formation consists of paralic siliciclastics over meters thick Fig. The clastics accumulated in delta-front, delta-topset, and fluvio-deltaic environments. In the lower Agbada Formation, shale and sandstone beds were deposited in equal proportions, however, the upper portion is mostly sand with only minor shale interbeds.
The Agbada Formation is overlain by the third formation, the Benin Formation, a continental latest Eocene to Recent deposit of alluvial and upper coastal plain sands that are up to m thick Avbovbo, Depobelts Deposition of the three formations occurred in each of the five offlapping siliciclastic sedimentation cycles that comprise the Niger Delta.
These cycles depobelts are kilometers wide, prograde southwestward kilometers over oceanic crust into the Gulf of Guinea Stacher, , and are defined by synsedimentary faulting that occurred in response to variable rates of subsidence 3 and sediment supply Doust and Omatsola, The interplay of subsidence and supply rates resulted in deposition of discrete depobelts--when further crustal subsidence of the basin could no longer be accommodated, the focus of sediment deposition shifted seaward, forming a new depobelt Doust and Omatsola, Each depobelt is a separate unit that corresponds to a break in regional dip of the delta and is bounded landward by growth faults and seaward by large counter-regional faults or the growth fault of the next seaward belt Evamy and others, ; Doust and Omatsola, Five major depobelts are generally recognized, each with its own sedimentation, deformation, and petroleum history fig.
Doust and Omatsola describe three depobelt provinces based on structure. The northern delta province, which overlies relatively shallow basement, has the oldest growth faults that are generally rotational, evenly spaced, and increase their steepness seaward. The central delta province has depobelts with well-defined structures such as successively deeper rollover crests that shift seaward for any given growth fault.
Last, the distal delta province is the most structurally complex due to internal gravity tectonics on the modern continental slope. The belt extends from the northwest offshore area to the southeast offshore and along a number of north-south trends in the area of Port Harcourt fig. It roughly corresponds to the transition between continental and oceanic crust, and is within the axis of maximum sedimentary thickness see isopach map in fig. This hydrocarbon distribution was originally attributed to timing of trap formation relative to petroleum migration earlier landward structures trapped earlier migrating oil.
Evamy and others , however, showed that in many rollovers, movement on the structure-building fault and resulting growth continued and was relayed progressively southward into the younger part of the section by successive crestal faults, concluding that there was no relation between growth along a fault and distribution of petroleum.
Ejedawe relates the position of the oil-rich areas within the belt to five delta lobes fed by four different rivers. He states that the two controlling factors are an increase in geothermal gradient relative to the minimum gradient in the delta center and the generally greater age of sediments within the belt relative to those further seaward. Together these factors gave the sediments within the belt the highest "maturity per unit depth.
Haack and others relate the position of the oil-rich belt to oil-prone marine source rocks deposited adjacent to the delta lobes fig. Outside of the "oil-rich belt" central, easternmost, and northernmost parts of the delta , the gas:oil ratios GOR are high. The GOR within each depobelt increases seaward and along strike away from depositional centers. Stacher , using sequence stratigraphy, developed a hydrocarbon habitat model for the Niger Delta fig.
Pre-Miocene Akata shale was deposited in deep water during lowstands and is overlain by Miocene Agbada sequence system tracts. The Agbada Formation in the central portion of the delta fits a shallow ramp model with mainly highstand hydrocarbon-bearing sands and trangressive sealing shale system tracts--third order lowstand system tracts were not formed.
Faulting in the Agbada Formation provided pathways for petroleum migration and formed structural traps that, together with stratigraphic traps, accumulated petroleum.
The shale in the transgressive system tract provided an excellent seal above the sands as well as enhancing clay smearing within faults. Gas caps are common. Many reservoirs are overpressured and primary production is mainly from gas expansion Kulke, The size and depth distribution of oil and gas fields is shown in Figure Properties of Oil and Gas The physical and chemical properties of the oil in the Niger Delta are highly variable, even down to the reservoir level.
Organic geochemical profiles for a nonbiodegraded and moderately biodegraded Niger Delta oil are summarized in Figure Most oils fall within one of two groups. The second group of oils are biodegraded and from shallow reservoirs. The concentration of sulfur in most oils is low, between 0. A limited data set Mbendi, ; Nwachuku and others, shows a negative correlation between API gravity and sulfur content, suggesting that sulfur content is likely related to oil degradation.
This trend, however, is not seen in the data presented in Figure Oils derived from terrestrial organic matter such as those in the Niger Delta have high pristane:phytane ratios fig. If the oils are derived from terrestrial organic matter younger than mid-Cretaceous, then the oleanane:C 30 -hopane ratios are high as well fig.
These trace-metal data, together with the organic geochemistry and physical properties of the oil indicate that the Niger Delta source rocks contain predominately terrestrial organic matter. The organic matter was deposited in suboxic-anoxic bottom waters where vanadyl and nickel availability for bonding was hindered in part by formation of hydroxides and complexing with metastable sulfide ions, respectively.
Preservation of the organic matter would be quite good under these conditions. Hydrogen sulfide is not a problem associated with Niger Delta gas; however, relatively high mercury concentrations have been observed.
Energy Information Administration, b. Possibilities include variable contributions from the marine interbedded shale in the Agbada Formation and the marine Akata shale, and a Cretaceous shale Weber and Daukoru, ; Evamy and others, ; Ejedawe and others, ; Ekweozor and Okoye, ; Ekweozor and Daukoru, ; Lambert-Aikhionbare and Ibe, ; Doust and Omatsola, ; Stacher, ; Frost, ; Haack and others, Agbada-Akata The Agbada Formation has intervals that contain organic-carbon contents sufficient to be considered good source rocks see data in Ekweozor and Okoye, ; Nwachukwu and Chukwura, The intervals, however, rarely reach thickness sufficient to produce a world-class oil province and are immature in various parts of the delta Evamy and others, ; Stacher, The Akata shale is present in large volumes beneath the Agbada Formation fig.
Based on organic-matter content and type, Evamy and others proposed that both the marine shale Akata Fm. Ekweozor and others used ab-hopanes and oleananes to fingerprint crude with respect to their source--the shale of the paralic Agbada Formation on the eastern side of the delta and the Akata marine-paralic source on the western side of the delta.
Ekweozor and Okoye further constrained this hypothesis using geochemical maturity indicators, including vitrinite reflectance data, that showed rocks younger than the deeply buried lower parts of the paralic sequence to be immature. They derived a different thermal maturity profile, showing that the shale within the Agbada Formation is mature enough to generate hydrocarbons.
In other parts of the delta, they believe that both shales source the oil. Doust and Omatsola conclude that the source organic matter is in the deltaic offlap sequences and in the sediments of the lower coastal plain. Their hypothesis implies that both the Agbada and Akata Formations likely have disseminated source rock levels, but the bulk will be in the Agbada Formation.
In deep water, they favor delta slope and deep turbidite fans of the Akata Formation as source rocks. The organic matter in these environments still maintains a terrestrial signature, however, it may be enriched in amorphous, hydrogen-rich matter from bacterial degradation. Stacher proposes that the Akata Formation is the only source rock volumetrically significant and whose depth of burial is consistent with the depth of the oil window. Cretaceous Some have proposed that marine Cretaceous shale beneath the Niger Delta is a viable source rock e.
This Cretaceous section has never been drilled beneath the delta due to its great depth; therefore, no data exist on its source-rock potential. No data exist to support such a network. The chemical composition of the oils provides conflicting evidence for the hypothesis of a Cretaceous source rock, especially for an Early Cretaceous one.
Significant oleanane is found in Niger Delta crude. This compound is related to angiosperms, which only became wide spread in the Late Cretaceous-Tertiary. Haack and others use the northern Gulf of Mexico Basin model of older rocks sourcing oils in deeper water to suggest that oil in hypothetical deep-water plays of the Niger Delta may be sourced, in part, by Upper Cretaceous rocks.
As these oils are in hypothetical plays, no geochemical data are available yet to test such a hypothesis in the Niger Delta. Source Rock Chemical Characteristics Bustin , in a detailed source-rock study on side-wall core and cuttings from the Agbada-Akata transition or uppermost Akata Formation, concluded that there are no rich source rocks in the delta.
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