Preface

Mangroves' remarkable biology and ecosystem are vital to our planet's health and well-being, demanding our unwavering commitment to conservation. The mangrove ecosystem provides indispensable ecological services, strengthening coastal resilience, promoting biodiversity, and underlining the urgent need for protection.

Chapter 1, "Mangroves of the Niger Delta", by Izuchukwu Uche, and Chapter 2, "The Niger Delta Mangrove Ecosystem and Its Conservation Challenges", by Anthony E. Ogbeibu and Blessing J. Oribhabor, explore the rich and extensive mangroves in Africa, which provide ecosystem services to the community, outline the threats to the mangrove ecosystem, and recommend strategies and conservation efforts to sustain the Niger Delta mangrove forest.

Mangroves' growth, development, and proliferation greatly depend on their biophysicochemical substrate. Chapter 3, "Perspective Chapter: Remarks on the Relationship of Mangrove Recruitment and Thrombolithic Development in Coastal Lagoons", by David Alfaro Siqueiros Beltrones, documents the thrombolithic formations associated with mangrove forest substrate. The findings presented in this study shed new light on the intricate relationship between mangrove recruitment and the development of thrombolytic formations, which play a vital role in the geomorphological dynamics of coastal areas.

Despite efforts to conserve the fragile mangrove ecosystem, this unique environment is constantly influenced by anthropogenic activities. Chapter 4, "Perspective Chapter: Mangrove Deforestation and Sustainability of Malacological Resource Exploitation in the Estuarine Ecosystem of the Saloum River Delta, Senegal", by Hamet Diaw Diadhiou, Moustapha Deme, and Djiby Thiam, provides insights into the anthropogenic activities and sustainability of malacological resources in the estuarine ecosystem.

Proper management of mangroves greatly depends on the periodic health assessment of the ecosystem. Chapter 5, "Mangrove Health Assessment Using Hemispherical Photography: A Case Study on Mangrove Ecosystem for Ecotourism at Tajungan-Bangkalan, Madura Island, Indonesia", by Maulinna Kusumo Wardhani, highlights the critical role of mangrove health assessment for the sustainable use and management of the ecosystem. Using hemispherical photographic analyses, the observation of mangrove percent cover, monitoring, and assessment become more efficient. The findings of the study are invaluable in mangrove rehabilitation, conservation, and educational ecotourism.

Ecosystem-based coastal protection is integral to the success of the mangrove development program. Chapter 6, "Mangroves and Ecosystem-Based Coastal Protection in the Mekong River Delta, Vietnam", by Klaus Schmitt and Thorsten Albers, explores

the anthropogenic and natural threats to the mangrove ecosystem in the Mekong River Delta. The chapter also highlights the ingenious and cost-effective strategies to reduce erosion and restore tidal flats for mangrove regeneration.

Finally, Chapter 7, "Perspective Chapter: Mangrove Conservation – An Ecotourism Approach", by I. Ketut Ginantra, investigates the uniqueness and diversity of the mangrove ecosystem. This ecosystem's diverse flora and fauna are platforms for scientific exploration and ecotourism. Principles and perspectives on mangrove conservation, ecology, economy, and community evaluation are well presented.

I sincerely thank all authors for sharing their esteemed works. I hope this book will inspire readers to explore and protect the astounding mangroves of the world.

**Dr. Orlex Baylen Yllano**

Professor and Chair, Department of Biology, College of Science and Technology, Adventist University of the Philippines, Silang, Cavite, Philippines

## **Chapter 1** Mangroves of the Niger Delta

*Izuchukwu Uche*

#### **Abstract**

The Niger Delta is located in the southern part of Nigeria; three core states, Rivers, Bayelsa, and Delta house the largest concentration of Mangroves. The Niger Delta has the most extensive mangroves in Africa; six true mangrove species are found in the Niger Delta, *Rhizophora spp*. (*R. mangle, R. harrisonii, R. racemosa*) Known as red mangrove; Avicenna *germinans,* known as black mangrove*; Langucularia racemosa,* known as white mangrove*; and Conocarpus erectus,* known as buttonwood*. Rhizophora spp.* is the dominant mangrove in the Niger Delta and constitutes over 90% of the entire mangrove species in the region. Niger Delta mangroves are essential in providing ecosystem goods and services to the people. Unfortunately, the Niger Mangrove ecosystem faces severe threats from crude oil spills resulting from equipment failure, bunkering, vandalisation, and illegal refining. The invasion of mangroves by Nipa palm in the Niger Delta has become a threat to the mangrove ecosystem; deforestation and urbanisation are also significant threats affecting mangroves in the region. Providing sustainable alternatives to mangrove forest wood, conservation of mangrove forests, and enforcement of strict regulations in the oil and gas industry are some measures to ensure the sustainability of the Niger Delta mangrove forest.

**Keywords:** Niger Delta, mangrove, oil spill, Nipa palm, ecosystem, remediation, forest

#### **1. Introduction**

The Niger Delta region of Nigeria is home to Africa's largest mangrove forest and one of the world's most extensive mangrove forests. The area of mangrove forest habitat coverage in Nigeria is estimated at 8442.43 km2 [1]. The Niger Delta region is located in the southern part of Nigeria; this region contains the majority of the mangrove forest in the country. Mangroves are trees and shrubs that grow on intertidal coastlines of tropical and subtropical regions. Mangroves are salt-tolerant plants that survive mostly in brackish water. In the Niger Delta, four mangrove genera exist; Rhizophora, Aviecina, Langucularia, and Conocarpus. *Rhizophora spp.* include *R. racemosa, R. mangle and R. harrisonni.* Other mangrove species in the Niger Delta are *Langucularia racemosa*, *Avicennia germinans*, and *Conocarpus erectus*. *Rhizophora sp. Langucularia racemosa and Aviecina germinans* are also known as red, white, and black mangroves, respectively, while *C. erectus* is known as buttonwood in the Niger Delta [2, 3]. Red mangroves are easily identified in the Niger Delta by their prop roots, leaves, and propagules; white mangroves are easily identified by their oval leaves, fruits, and seeds; and black mangroves can easily be distinguished from other mangroves by their elongated leaves, fruits, and seeds, including the presence of pneumatophores.

Mangroves in the region have been severely depleted; just like mangroves worldwide, mangroves in the Niger Delta are being lost at an alarming rate. However, data are readily not available for the hectares of mangrove forests lost over the last two decades in the Niger Delta. Several researchers have reported significant losses. Today's leading cause of mangrove loss in the Niger Delta is crude oil spills and artisanal refining [4]. Other factors have also been reported to cause the loss of mangrove forests in the region: urbanisation, conversion of mangrove forests for agriculture and aquaculture, construction, deforestation, overpopulation, and the invasion of nipa palm in the mangrove ecosystem. The importance of the mangrove ecosystem has been widely researched and documented, so the need to protect and preserve these ecosystems becomes very dire owing to their uniqueness and myriads of ecosystem goods and services [5].

While the degradation and destruction of mangrove forests in Africa's most extensive mangrove continues, efforts have been made to restore hectares of mangrove forest destroyed by a crude oil spill. One such effort is a litigation case between a small community in River's state and an international oil and gas company operating in the region, where an agreement was reached between the community and the international oil and gas company to clean up and revegetate approximately 1000 ha of degraded mangrove forest in the community. Furthermore, the United Nations Environmental Program (UNEP) report [6] led a government agency to clean up the oil spill in Ogoniland and revegetate damaged mangrove forests, among other functions. While clean-up and revegetation efforts have commenced in the earlier case study, clean-up is currently ongoing in the government-managed cleanup process in Ogoniland [7, 8].

#### **2. The Niger Delta**

The Niger Delta of Nigeria is among the largest delta in the world. A delta is a landform that originates due to depositions of sediments carried by a river as the flow leaves the mouth of the river and enters slower-standing or moving water. Deltas occur when a river joins a sea or an ocean and cannot transport away the supplied sediments. The Niger Delta region has the largest wetland in Africa and the third-largest wetland in the world. Projections of the estimate of the current population in the region at a growth rate of 2.9% place the population of the Niger Delta as of 2022 to be well over 45 million people. The core Delta areas in the region lie in three central states: Delta, Rivers, and Bayelsa; these three states hold the most significant amount of mangrove forest in the country. Politically the Niger Delta region in Nigeria comprises nine states: Abia, Akwa Ibom, Cross River, Edo, Imo, and Ondo states, including the core states of the Niger Delta [9]. **Figure 1** shows the map of Nigeria and the extent of coverage and distribution of mangrove forests in the Niger Delta and Nigeria.

Other states with mangroves in Nigeria include Akwa Ibom, Cross River, Ondo, Ogun, and Lagos. The mangroves of the Niger Delta are located in the lower tidal floodplain, which also comprises various creeks and estuaries. The delta has a very high rainfall of more than 2500 mm per year, with a temperature range from 18 to 30°C. The tide in the mangrove forest is diurnal and can reach an amplitude of 2.8 m during spring tide and 0.2 m at the shallow tide. The poverty rate in the Niger Delta is at an average of 30%, and the region is densely populated with a literacy rate of 70%. Most rural dwellers are into fishing and farming and mostly depend on forests and surrounding water bodies for their primary source of income and survival [9].

**Figure 1.** *Map of Nigeria showing areas of mangrove coverage in the Niger Delta and Nigeria.*

The Niger Delta is also an extremely prolific hydrocarbon province where oil and gas have been explored and exploited over decades. A significant percentage of Nigeria's oil and gas facilities run through the mangrove forest in the region; this has led to the rapidly under-reported degradation of mangroves in the region either by direct or indirect consequences of oil and gas exploration. Crude oil spills resulting from equipment failure, sabotage, bunkering, and artisanal (illegal) refining in the region have destroyed vast hectares of mangrove forest in the entire Niger Delta. Although the extent of the destruction is not known throughout the entire region, significant damage to the mangrove forest has been reported in the past by researchers [4, 10, 11].

#### **3. Mangrove autecology in the Niger Delta**

#### **3.1 Red mangrove**

*Rhizophora spp.* is the dominant mangrove species in the Niger Delta; it is distributed on all intertidal mangrove platforms and is found in almost all forest zones in the region. Mangrove platforms are areas where mangroves thrive; platforms are mostly intertidal areas in a mangrove forest. *Rhizophora spp*. Consist of over 90% of the total mangrove plant in the Niger Delta forest. Three species of Rhizophora exist in the Niger Delta: *Rhizophora racemosa, Rhizophora mangle, and Rhizophora harrisonii*. The differences between *Rhizophora* species in the Niger Delta can mainly be observed when the plants are fruiting. These distinctions are only observable once the plants mature enough to bear fruits. For this reason, it is not easy to differentiate the various

*Rhizophora* species. *Rhizophora racemosa* is dominant among the three species, according to [2, 3]; in some instances, a different *Rhizophora* species is dominant in a different mangrove forest in the Niger Delta. Rhizophora mangroves have been known to grow as tall as 25-30 m in a pristine mangrove forest. They can be clearly distinguished by their prop root, which drops down from tree trunks and branches as high as 10 m in some plants, and the prop root mostly touches the soil or can be suspended in the air. Their prop roots have tiny pores all over them, which are used for gaseous exchange; these pores are known as lenticels. All year round, red mangroves in the Niger Delta flower exhibit a form of reproduction known as vivipary, where flowers develop into seedlings while still attached to the parent plant. Rhizophora seedlings are often referred to as propagules. Rhizophora propagules are distinct from other species in the Niger Delta. Thus, due to their dominance, most people confuse them for being the only mangrove species in the Niger Delta. Rhizophora propagules fall off the parent plant upon maturity and are carried by tidal currents until it finds suitable soil where it roots itself and begins to grow. Red mangroves are the most cultivated mangrove in nurseries all over the region (**Figure 2**). Shows various life stages of a typical red mangrove plant in the Niger Delta, its prop root, and propagules.

#### **3.2 Black and white mangrove**

White and black mangroves make up less than 10% of the total mangrove species population in the region. White mangroves clearly distinguish from black mangroves in the Niger Delta as seen from their leaves. The leaves of white mangroves are oval in shape with a thick, dark green colouration in most cases, while the leaves

#### *Mangroves of the Niger Delta DOI: http://dx.doi.org/10.5772/intechopen.109296*

of black mangroves are elongated and attenuated with a light green colouration. Also, one common feature of black mangroves that distinguishes them from white mangroves is the presence of pneumatophores. Pneumatophores are the lateral root that grows out of the soil, also used for gaseous exchange by black mangrove plants. Pneumatophores are found on all black mangrove plants, extending as far as 10 m from the parent plants in matured black mangrove plants. White mangroves can grow into trees but are mainly shrubs in the Niger Delta; some white mangrove plants have pneumathodes similar to black mangrove pneumatophores but are not the same and are not found on all white mangrove plants in the region. In the Niger Delta, white and black mangroves are always found in the intertidal zones of the mangrove forest.

In contrast, black mangroves are majorly found along shorelines where the sediments contain lots of sand; black mangroves are also found on intertidal platforms where the sediments are dominated by mud. White mangroves also grow on muddy and sandy sediments like black mangroves, but they also thrive on the fringes of platforms close to the channel edges [3]. **Figure 3** shows black and white mangrove plants and their different life stages.

#### **3.3 Buttonwood**

Buttonwood is the least common mangrove species in the Niger Delta, and they are less than 1% of the total mangrove population in the region. Buttonwood grows majorly high up the platform in the mangrove forest of the Niger Delta; they are found in areas close to the high tide swash line on the platform; buttonwood does not grow on intertidal zones in the Niger Delta and grows best on sandy sediments. Their leaves are elongated and attenuated with dark green colouration, and their seeds are round and green but turn brownish red upon maturity. **Figure 4** shows a buttonwood mangrove plant in the Niger Delta and its seeds (propagule).

#### **Figure 3.** *Is black and white mangrove plants showing their various life stages.*

**Figure 4.** *Shows a buttonwood mangrove plant in the Niger Delta and its seeds.*

#### **3.4 Mangrove associate species in the Niger Delta**

Nipa palm, although an exotic species in the region, is also referred to as a mangrove associate plant despite the plant invasion of the mangrove forest in the region. Other commonly found associate mangrove species found in the region's mangrove forest are mangrove fern (*Achrostichum aureum*), mangrove grass (*Paspalum vaginatum*), and wild palm (*Phoenix reclinata*). All later species mentioned are not invasive but can be found in a different zone and intertidal areas in a mangrove forest. Mangrove fern is evenly distributed on almost all mangrove platforms; mangrove grass is mainly found on shorelines, sandy sediments, and areas close to the high tide swash line along the mangrove platform. The wild palm grows along the buttonwood corridor but is sometimes found on the intertidal platform. Wild palm and mangrove ferns grow mainly as shrubs in the region. **Figure 5** shows mangrove fern and wild palm in a mangrove forest in River's state.

#### **3.5 Mangrove zonation in the Niger Delta**

**Figure 6** below is a drone picture of a remediated mangrove forest platform with little vegetation. The arrows indicate areas where each mangrove species will likely grow in the Niger Delta. The yellow arrow indicates the intertidal zone of the platform, and the yellow arrowhead to the right is the high tide swash line. In a pristine mangrove forest, due to the dominance of red mangroves, they mostly occupy the intertidal zones, as noted by the red arrow in the picture below. White mangrove also thrives in areas where red mangrove thrives but are outcompeted by red mangrove, as seen from the white arrow in the picture. Black mangroves thrive best at the upper platforms and shorelines, as indicated by the black arrow in the picture. Buttonwood typically grows in areas outside the intertidal zone or close to the mangrove high tide swash line, or it can grow in higher platforms with minor inundation. In a degraded mangrove forest, black, white, and red mangroves can thrive in any intertidal area in a mangrove platform in the Niger Delta.

#### **3.6 Sediment types in a typical Niger Delta mangrove forest**

The sediment in a typical Niger Delta mangrove forest varies from platform fringes, which are usually composed of pure mud, down to the intertidal

#### **Figure 5.**

*Shows mangrove fern and wild palm common mangrove associate plant in the Niger Delta.*

#### **Figure 6.**

*Below is a drone picture of a remediated mangrove forest platform with little vegetation. The arrows indicate areas where each mangrove species will likely grow in the Niger Delta.*

platform, where a mix of mud and Chikoko roots start to build up, down to the inner fringe of the platform and shoreline, which consist of mud, Chikoko root and sand. Chikoko roots are the thick fibrous peaty composition of mangrove roots, leaves, and other organic components of mangrove plants that have decayed over a long period and are often found in the sediments of mangrove soils. In some mangrove platforms, these fibrous peaty materials are found as deep as 1 m when you dig the soil of the mangrove platform. In certain areas, Chikoko roots make up over 95% of the entire soil sediment in the Niger Delta. Sandy soil is a significant sediment found in mangrove platforms and often along the shoreline and areas close to the high tide swash line on the platform. Soil sediments also vary from one location to the other in the Niger Delta; specific platforms in some mangrove areas are composed of two or more sediment types in different proportions. Typically, muddy sediment is the dominant sediment type in Niger Delta; it is common to see a mixture of two or more sediment types mixed or in layers. A mixture of mud and Chikoko root is a common sight when you dig up to 30 cm beneath the surface [12]. **Figure 7** below shows various sediment types commonly found in the Niger Delta mangrove forest 0.3 m below the surface sediment.

**Figure 7.** *Below shows various sediment types commonly found in the Niger Delta mangrove forest at a depth of 30cm.*

#### **4. Threats to Niger Delta mangrove forest**

Over the years, mangroves in the Niger Delta have faced challenges common to mangroves forest worldwide: the conversion of mangrove habitats for agriculture and aquaculture. It is a common site in most mangrove areas in the Niger Delta for locals to construct fish ponds, where they rear fish and use such areas sometimes to trap fish at high tide. Areas converted to fish ponds are mainly mangrove forests cleared and used as fish ponds; in some instances, these fish ponds can be as large as 900sqm. Fishing in the Niger Delta is one of the biggest employers of labour for both men, women, and children living near mangrove habitats. Mangrove forests are cleared so nets can be used to set traps for fish; However, fish pond construction completely clears mangrove trees on the land where it is constructed; the surrounding mangrove environment is usually left undisturbed; the impact of the fish pond on the degradation of the Niger

#### *Mangroves of the Niger Delta DOI: http://dx.doi.org/10.5772/intechopen.109296*

Delta mangroves forest can be said to be minor when you assess the risk of fish pond construction in a mangrove forest in the Niger Delta.

Deforestation of mangrove forests is also a significant threat to mangroves in the Niger Delta. In the Niger Delta today, due to the high poverty and illiteracy level, most communities still use wood as their primary energy source. This has led to the constant deforestation of mangrove forests in the region. Mangrove trees make good wood for local consumption; logging trees in mangrove forests for commercial and subsistence purposes is a common site in the region. The need for cheaper energy sources and lack of alternative cheaper energy for cooking in the Niger Delta have been the reason for the constant deforestation of the Niger Delta mangrove forest. It is also common to see fishermen use deforested trees as sails for their boats. Deforestation has increased due to harsh economic realities and rising poverty levels, which have increased in the Niger Delta in the last decade. Steps must be taken to enlighten the locals on the dangers of deforesting mangrove forests. Still, most importantly, an alternative and a cheap source of cooking must be provided to the lowincome earners in the community to reduce the incidence of deforestation and reduce the dependence on the local community for the use of mangrove wood as a primary source of energy. **Figure 8** shows wood harvesters in Goi, a small Ogoni community, in boats returning to their base after harvesting mangroves.

Population growth, urbanisation, and construction are significant threats to the mangrove ecosystem in the Niger Delta. As the population of the people of the Niger Delta increases, the demand for forest products such as wood also increases. Population growth would automatically mean people require more land for farming, building, and other social needs and, by extension, additional pressure on the surrounding forest. Construction of roads and oil and gas facilities, such as pipeline networks, have extensively degraded mangrove forests in the Niger Delta. Proper enlightenment of the local community on the need to protect the forest must be a task that the government and civil societies would have to embark on so mangrove forest goods and services can be used sustainably in the Niger Delta. Despite the threat discussed so far, the effect of petroleum hydrocarbon spillage and the invasion of Nipa palm in mangrove habitat in the Niger Delta remain two of the biggest threats currently facing the Niger Delta mangrove forest at the moment and will be discussed broadly.

#### **Figure 8.**

*Shows wood harvesters in Goi Gokana LGA, a small Ogoni community, in boats returning to their base after harvesting mangroves.*

#### **4.1 Nipa palm invasion of mangrove forest in the Niger Delta**

*Nypa fruticans*, also known as Nypa or Nipa palm, are commonly found in Asia. They are large green palms forming loose clumps from a subterranean stem. Nipa palm has clumps of individual erect and large leaves that can grow as long as 6 m. In Asia, Nipa palm seeds and saps are edible and used for thatching. Nipa palms are not natural flora in the Niger Delta mangrove forest; their presence in the Niger Delta was due to their introduction in Calabar, Nigeria, in 1906 from a Singapore botanical garden. In 1964, thousands of seeds originating from Malaya were planted throughout the brackish swamps of the Niger Delta. These were the major points where Nipa was introduced to the Niger Delta. Introducing these plants in the Niger Delta provided an alternative palm for the people to the native palm (*Elaeis guineensis*), mainly used for thatching, food, and alcoholic wine [13]. It is safe to say that at the time these decisions were made, the value of mangroves had not been fully understood by those who made the decision, and the unintended consequences of Nipa palm invading the mangrove forest were not anticipated.

In the Niger Delta, Nipa palm has become an invasive species and is taking over mangrove habitat. Nipa palm can be found along the coastline of the Niger Delta mangrove forest down to Lagos and Ogun. Unfortunately, the local community does not use Nipa palm in the Niger Delta for any purpose, as they are not the palm of choice for thatching; their sap and seeds are edible in other parts of the world but are currently not eaten in Nigeria. Nipa palm grows on the fringes of the Niger Delta mangrove platform, competing with mangroves for space, food, and habitat, and expanding its reach when the opportunity provides itself. In a healthy, matured mangrove forest, the only available areas Nipa can grow are the fringes and sometimes channel edges of the mangrove platform and along the coastline.

The current degradation of mangrove forests in the Niger Delta has provided Nipa palms with the opportunity to thrive in areas where mangroves would naturally outcompete them in the Niger Delta. This has allowed Nipa palm to find its way into the heart of mangrove platforms and establish itself, thereby colonising areas where mangrove plants should grow. Nipa palm and mangroves have similar modes of seed dispersal; unfortunately, Nipa tends to outgrow and outcompete mangroves when the two plants are simultaneously established on the same soil in a mangrove habitat [14]. Nipa palm invasion of mangroves has been described as one of the significant threats to the mangrove ecosystem in the Niger Delta, the growth and spread of Nipa palm, if not checked, would spiral out of control. The current effort to stop the spread of the plant in the region has been to mechanically remove the plant from the mangrove habitat by cutting down the plant and taking their seeds away, as it is currently done in Bodo, a small Ogoni Community where restoration efforts are being made in the Niger Delta [7].

The sustainability of mechanical removal of Nipa palm would require a concerted effort of the entire Niger Delta and Nigeria, including its west African Neighbours whose coastlines have also been overrun by Nipa palm. Today Nipa palm has become not just an invasive species in the Niger Delta; it has also formed part of the associated mangrove species in the Niger Delta since their number cannot be overlooked and can no longer be considered an exotic species if nothing is done about their rapid growth and spread. **Figure 9** shows the Nipa palm growing on the fringes of a mangrove platform in the Niger Delta and the mechanical removal of the Nipa palm from a remediated mangrove forest in the Niger Delta.

**Figure 9.**

*Shows the Nipa palm growing on the fringes of a mangrove platform in the Niger Delta and the mechanical removal of the Nipa palm from a remediated mangrove forest in the Niger Delta.*

#### **4.2 Crude oil spills on mangroves in the Niger Delta**

Petroleum hydrocarbon is one of the vast natural resources in the Niger Delta and the primary income of Nigeria today. Unfortunately, the Niger Delta of Nigeria has been on the receiving end of many environmental disasters resulting from petroleum hydrocarbon pollution. In the Niger Delta, some oil and gas exploration well heads are located on mangrove forests, and vast networks of oil and gas pipelines in the Niger Delta run through mangroves forest or creeks and estuaries adjourning mangrove forests; this has made it possible for mangroves to be readily degraded by petroleum hydrocarbon whenever there is an accident, sabotage or equipment failure on any of these facilities. The oil spill history in the Niger Delta dates back to when commercial exploration of oil began in Oloibiri, current Bayelsa state, in February 1958. Since the commercial exploration of oil and gas in Nigeria, thousands of oil spill incidents have been reported in the Niger Delta. Some of these have been noted to affect mangrove habitat; one such incident where large-scale mangrove destruction occurred in the Niger Delta is in Ogoni and Bonny in River state, Nembe in Bayelsa state, and many other regions in the Niger Delta.

A case study of a significant oil spill incident in the Niger Delta happened in 2008 and 2009 along the Trans Niger Pipeline (TNP), which carries Bonny light crude oil to an export terminal in Bonny River State. The TNP is critical to Nigeria's crude oil export and is jointly operated by the Nigerian government and a major international oil and gas company; the TNP carries 180,000 barrels daily to the Bonny export terminal. In October 2008, there was a leak along the TNP, which happened to be along the creeks in a community known as Bodo. After a joint investigation, it was discovered that the leak was caused by equipment failure due to corrosion due to the old pipeline conveying crude, which was laid in the 1960s. Locals reported that the leaks in the pipeline occurred for weeks before it was clamped, and thousands of barrels of crude were spilled into the surrounding creeks, which eventually damaged hectares of mangrove forest along Bodo, Goi, Kpor, and Bomu in Gokana River state. In February 2009, another leak occurred in Bodo along the TNP, a few kilometres away from the previous leak; no data was put out on the exact amount of oil introduced to the environment. The effect of the two spills resulted in the degradation of over 1000 hectares of mangrove forest and the destruction of fauna and flora within and around the affected areas [15, 16].

#### **4.3 The effect of crude oil spill on mangroves**

Mangroves are susceptible to oil exposure depending on the degree of oiling, length of exposure, and, to an extent, the type of crude oil. Mangroves exposed to crude oil in sufficient amounts to cause harm will suffer from their leaves turning yellow and falling off (defoliation) and eventually death. The smaller and younger trees or plants whose stems and leaves are entirely coated by oil are usually among the first to die off because the plant's lenticels and leaves used for transpiration and salt excretion are covered with crude, thereby preventing the natural biological function of the entire plant [17].

Following the two spills in Bodo creek, crude oil floated freely on the surface of the creek; being an intertidal area, crude oil was constantly being carried into intertidal platforms where they are deposited on sediments, leaves, stems, and prop roots of mangroves. A few weeks after the spills, all plants that were coated with oil from their stems to their leaves died; it did not take long after areas that had high crude oil deposits, all plants gradually started dying off, and hectares of mangrove forest was left with stumps of interwoven dead mangrove plant. Years after the spill, the entire dead plant stumps collapsed, leaving an open island of degraded mangrove platform with dead mangrove stumps littered all over the platform.

The effect of crude oil on mangrove habitat has a ripple effect on the faunal community and the livelihood of the people who depends on mangroves for the many goods and services it provides to the locals in the community. Most Niger Delta communities, as noted earlier, are heavily dependent on fishing, and polluted creeks resulting from crude oil spills are often devoid of fish even after cleanup, it takes a significant amount of time for the fish communities in most of these creeks to be back to its pristine conditions. The cascading effect of spill damage on mangroves forest has been experienced in many Niger Delta communities in Ogoni Rivers State; due to the death of mangroves closer to the shorelines where the people reside, wood harvesters have had to go deeper into areas where the spill barely affected to harvest wood, this has put enormous pressure on the forest as trees which are not matured enough are harvested leading to rapid deforestation of the mangrove forest. Furthermore, the spill's effect on invertebrate and fish communities has put enormous pressure on the creeks due to the trawling of small and immature fish due to the depleted fish stock in the creeks. Juvenile mangrove plants have also been harvested in these areas, reducing the chances of natural recovery. As a result, human-mediated revegetation is required to restore the lost ecosystem.

Although the damage from a large-scale oil spill has acute and chronic implications, pollution from artisanal (Illegal) refining, bunkering, and crude oil theft have also destroyed hectares of mangrove forest in the Niger Delta, and most of these destructions are largely undocumented. Artisanal or illegal refining of crude oil in the Niger Delta, locally known as "Kpo-Fire," is the small-scale processing of stolen crude by heating it at high temperatures to distill it into its fractional components. The mangrove forests and other parts of the Niger Delta have become spots and makeshift refineries for artisanal refining crude oil. The implication of this is that mangroves are cleared to set up a refinery, and in most cases, mangrove trees are harvested to provide energy for heating the crude at very high temperatures; the effluent, tar, and asphalt, which are usually bi-product of the refined crude are often discharged in pits in or around the mangrove forest. Crude oil used for artisanal refining in the Niger Delta is stolen chiefly from pipelines running through the mangrove forest. The point at which the pipes are compromised, if not well-engineered, is usually a

#### *Mangroves of the Niger Delta DOI: http://dx.doi.org/10.5772/intechopen.109296*

source of spill in the mangrove forest; transportation of the crude and storage of the crude, including refined artisanal products, are usually significant spill sources in the Niger Delta. Artisanal refining camps in the Niger Delta have been on the increase in the Niger Delta despite several government clamps down; the more camps created, the more pressure on mangroves somewhere in the Niger Delta; unfortunately, most of the damage from artisanal refining and crude oil theft on mangrove forest is not documented as such the extent of damage caused by artisanal refining on mangrove forest in the Niger Delta today is difficult to quantify [10].

Despite the damage from the crude oil spill on mangroves in the Niger Delta, efforts are currently ongoing to restore hectares of damaged mangrove forest in the Niger Delta, mainly due to the UNEP report [6] and a few litigation cases between the host community and international oil and gas companies responsible for the spill in partnership with Nigerian government regulatory agencies. Some of these efforts have shown great restorative potential, and remediation, cleanup, and revegetation have begun in earnest.

#### **5. Mangrove restoration in the Niger Delta**

In the Niger Delta, mangrove restoration has been done mainly on a small scale. A mediation-driven mangrove restoration program is currently Nigeria's most extensive [18]. Although the government-backed cleanup of Ogoniland would involve mangrove restoration, the remediation phase of the cleanup of intertidal areas is currently ongoing. Mangrove forest impacted significantly by crude oil spills requires cleanup/ remediation of the contaminated mangrove sediments, planting, and monitoring of mangroves. Mangrove ecosystems are intertidal environments that are usually very challenging to clean up or remediate after a spill. For the first time in the Niger Delta, the shoreline cleanup assessment technique (SCAT) has been deployed to clean up/ remediate contaminated mangrove sediment in the Niger Delta [7, 16].

#### **5.1 The use of SCAT in the Niger Delta**

The Exxon Valdez spill in 1989 birthed the origin of SCAT, and since then, the technique has been used in several spill cleanups globally. SCAT was first used in the Niger Delta in 2019 and is currently used to clean up spill sites in the Niger Delta. SCAT involves a series of surveys before, during, and after the cleanup/remediation operation. SCAT rapid surveys are initial surveys done during the SCAT process to determine the level of contamination and areas affected by the spill. The SCAT rapid survey serves as a baseline where blueprints for remedial/cleanup actions are designed. SCAT assessment surveys are done to delineate work areas and get in-depth information to characterise work areas. SCAT confirmation or verification surveys are done after cleanup/remedial actions have been done in the affected areas [19].

SCAT process requires the participation of all stakeholders in the remediation process; stakeholders in the Niger Delta usually include the host communities, the oil and gas company, government regulatory agencies, a mediation body (if set up), and civil society organisations. Representatives of all stakeholders would be available at all stages of the SCAT process. Cleanup or remediation is given to contractors with expertise in oil spill remediation. The stakeholders often agree upon remediation techniques, and the SCAT team confirms remediation work. The SCAT team is composed of a representative of all stakeholders at every site or work area to be

confirmed; SCAT confirmation is done by digging three pits and assessing the level of oiling in the pit. SCAT assessors are usually trained in SCAT techniques to assess the pit; remediated site maps are designed and produced by the management and SCAT team lead, and coordinates of the sites are handed over to the SCAT team for verification and confirmation.

Pit oiling assessment is critical to verifying and confirming remediated sites; in the cleanup process at Bodo, pit oiling assessment for confirmation of a site is a maximum of 25% oiling per pit. A work area can have as many sites as possible, depending on the size of the area. Irrespective of the number of sites in the remediated area, each site must have three pits, usually in a trisection, with the sum of pit oiling in all three pits less than 75%. Although this process is subjective and open to bias, the oiling level for each pit is agreed upon by the entire stakeholders in the SCAT team. A standard pit oiling chart also guides the SCAT team in their assessment when determining oiling levels in the pit.

#### **5.2 Mangrove planting and monitoring**

After cleanup/remediation is completed, the next phase of the restoration program is planting mangroves. In the Niger Delta, mangroves are planted as propagules, sprouted propagules, or seedlings. While propagules are seeds from mangrove plants (**Figures 1**–**4**) harvested and put directly on restoration sites to grow, sprouted propagules and seedlings are grown or nursed in a nursery before being transplanted to their restoration site after a certain period. Seedlings are preferred as the life stage of choice in the Niger Delta for restoration, as observed in the Bodo revegetation projects. Seedling also increases restoration costs but improves the survivability of the overall plants during restoration. Seedlings will require the setting up nurseries, usually found in some Niger Delta communities close to intertidal areas. Nurseries are sited close to intertidal areas to avoid the constant need to water the plant with brackish water when the nursery is located far away from intertidal areas [20].

Most mangrove nurseries in the Niger Delta have only *Rhizophora spp.* Seedlings grown in them might be unconnected with the fact that *Rhizophora spp.* is the dominant mangrove species in the Niger Delta, and most locals in the community do not see other mangrove species as part of the mangrove community in the Niger Delta. Mangrove planting involves transporting mangrove seedlings to areas where they would be transplanted; care must be taken during transportation since some mangrove areas might be inaccessible on foot. Mangrove seedlings should be planted in a single bag, although to save cost, specific mangrove nurseries in the Niger Delta plant multiple propagules in a single bag. Single bags are advised to reduce stress on the plant during transplanting and to ensure that the soil and the plant are placed in the ground together. **Figure 10** shows a mangrove nursery in the Niger Delta and how propagules are planted in single and multiple propagules per bag.

Monitoring mangroves is done to ensure their growth and survivability and to identify areas where significant losses occur, the cause(s) of the loss, and the need to replant after identifying why the loss occurred. Mangrove monitoring is critical to the survivability and growth of large-scale mangrove revegetation programs. The monitoring program in Bodo involves collecting specific data from marked plants in different planting areas. Monitoring is done at intervals of one, six, 12, and 18 months; specific data such as the increase in height, number of leaves and branches, oiling conditions number of prop roots or pneumatophores are collected at every monitoring interval. An overall count of the number of dead mangroves is done after the first

**Figure 10.** *Is a picture of a mangrove nursery in the Niger Delta and how propagules are planted in single and multiple propagules per bag.*

month of planting, where deaths exceed 5%; in a delineated planting area, the dead plants are replaced, and monitoring is scheduled for another month after replacing the dead plants. The process is repeated till the death rate in a particular planting area is less than 5%. Restoration of mangrove habitat is a long-term project as mangroves take years to fully mature.

#### **5.3 Challenges of mangrove restoration in the Niger Delta**

Corruption, weak government regulatory system, and lack of environmental justice have been the bane of mangrove forest restoration in the Niger Delta. Oil spills in mangrove ecosystems remain un-remediated, and where remediation Is done, they need to be done correctly. Also, most Niger Delta communities impede the cleanup process by demanding outrageous amounts from the oil and gas companies even after compensation has been paid out; in some cases, community leaders demand money to be used for the cleanup process be paid to them.

#### **6. Conclusion**

Mangroves of the Niger Delta are the largest and one of the most threatened mangrove ecosystems in Africa. The Niger Delta mangrove is a very significant ecosystem in the Niger Delta as they provide a variety of environmental, economic, and social goods and services to the people of the Niger Delta. Unfortunately, the importance of this vital ecosystem is not well known by most people in the Niger Delta; as such, the Niger Delta mangroves are depleted in certain areas at an alarming rate. Significant threats to the Niger Delta mangroves include Nipa palm invasion, oil spill pollution, deforestation, and urbanisation. Mangroves in the Niger Delta must be protected from the threats it is currently facing for the sustainability of this vital ecosystem. It is also essential to educate the communities around mangrove areas on the importance of protecting these forests; the government must, as a matter of national interest, map out areas of the Niger Delta mangrove forest for conservation; this would ensure the sustainability of the mangroves.

Conservation is a long-term strategy for protecting the Niger Delta mangroves; in the interim, both national and state governments must collaborate with all state actors in the oil and gas industry in the region to ensure the complete cessation of spills in mangroves and other parts of the Niger Delta, and as a matter of urgency stop illegal bunkering and artisanal refining of crude in the Niger Delta. A policy framework must also be drawn up on how to control the rapidly spreading Nipa palm currently invading mangrove forest in the region. Despite the significant threats affecting the mangroves in the Niger Delta, the sustainability of the region's mangroves is still very realistic if current threats are addressed.

#### **Acknowledgements**

I want to acknowledge Dr. Erich Gundlach of the Bodo Mediation Initiative, under whose platform I have been able to learn about the mangroves of the Niger Delta. I also appreciate his mentorship skills and willingness to impart knowledge. Special thanks to my colleagues Nicholas Story, Peter Lenu, and Bariton Lezabby for contributing to various aspects of this book chapter.

#### **Author details**

Izuchukwu Uche Centre for Environmental Management and Control, University of Nigeria, Enugu, Nigeria

\*Address all correspondence to: izucals@gmail.com

© 2022 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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[3] Zabbey N, Tanee BG. A Training Manual on Mangrove Restoration in Coastal Communities of the Niger Delta Nigeria. CEHRD, Port Harcourt Nigeria: Mobility Concept Press; 2021. p. 38

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[5] Numbere AO. Mangrove habitat loss and the need for the establishment of conservation and protected areas in the Niger Delta, Nigeria. In: Muscarella CM, Ortiz AC, Canas RQ, editors. Habitats of the World – Biodiversity, and Threats. London: IntechOpen. DOI: 10.5772/ intechopen.89623

[6] UNEP. Environmental assessment of Ogoniland, United Nations Environment Programme, Nairobi, 257. 2011. Available from: http://www.unep.org/nigeria. [Accessed: 23/10/2022]

[7] Gundlach ER, Iroakasi O, Story NI, Nwabueze V. Bodo Project, Ogoniland, Eastern Niger Delta. Part 2 – Innovative close-out procedures for oil-contaminated mangrove habitats. International Oil Spill Science Conference, Halifax, Canada, 21-25 March 2022. 2022

[8] Iroakasi O, Gundlach ER, Devaull G, Nwabueze V, Bonte M. Bodo Project, Ogoniland, Eastern Niger Delta. Part 1 – Application of RBCA and NEBA to determine site-specific target levels. International Oil Spill Science Conference 2022 March 21-25, Halifax, Canada. 2022

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[11] Ikezam P, Elenwo EI, Oyegun CU. Effects of artisanal refinery on the environment, public health and socioeconomic development of communities in the Niger Delta region. Environmental Management and Sustainable Development, Macrothink Institute. 2021;**10**(3):97-111. Available from: https://ideas.repec.org/a/mth/ emsd88/v10y2021i3p97-111. html

[12] Gundlach ER, Giadom FD, Akpokodje EG, Bonte M, Tse AC, Ekeocha NE, et al. Core sediments and oil chemistry from contaminated mangroves in eastern Niger Delta, Ogoniland, Nigeria. Marine Pollution Bulletin. 2021:171 112714. DOI: 10.1016/j. marpolbul.2021.112714

[13] Isebor CE, Ajayi TO, Anyanwu A. The incidence of Nipa Fruticans and its impact on fisheries production in the Niger Delta Mangrove ecosystem. 16th Annual Conference of the Fisheries Society of Nigeria (FISON) 4-9 November 2001 Maiduguri, Nigeria. 2011. pp. 13-16. Available from: http:// hdl.handle.net/1834/21300

[14] Numbere AO. Effect of soil types on growth, survival, and abundance of mangrove (*Rhizophora racemosa*) and Nypa Palm (*Nipa fruticans*) Seedlings in the Niger Delta, Nigeria. American Journal of Environmental Sciences. 2019;**15**(2):55-63. DOI: 10.3844/ ajessp.2019

[15] Pegg S, Zabbey N. Oil and water: The Bodo spills and the destruction of traditional livelihood structures in the Niger Delta. Community Development Journal. 2013;**48**(3):391-405. DOI: 10.1093/cdj/bst021

[16] Gundlach ER, McArthur A, Iroakasi O, Bonte M, Giadom FD, Shekwolo P, et al. Cleanup and restoration of 1000-ha of oiled Mangroves, Bodo, Eastern Niger Delta, Nigeria. IOSC Proceedings. 2021;**1**:1-25. DOI: 10.7901/2169-3358-2021.1.688932

[17] Wilson M, Hale C, Maung-Douglass E, Partyka M, Sempier S, Skelton T, et al. Impacts of Oil on Mangroves. Oil Spill Science: Sea Grant Programs of the Gulf of Mexico; 2019. (GOMSG-G-19-010)

[18] Gundlach ER, Bonte M, Story NI, Iroakasi O. Using highresolution imagery from 2013 and 2020 to establish baseline vegetation in oil-damaged mangrove habitat before large-scale post-remediation planting in Bodo, Eastern Niger Delta, Nigeria. Remote sensing applications: Society and Environment. 2022;**28**:100831. DOI: 10.1016/j.rsase.2022.100831

[19] Environment and Climate Change Canada (ECCC). Shoreline cleanup assessment technique (SCAT) manual. In: Triox Environmental Emergencies, Owens Coastal Consultants. 3rd ed. Ottawa: Environmental Mapping Ltd; 2018. p. 40

[20] Zabbey N, Tanee F. Assessment of Asymmetric Mangrove Restoration Trials in Ogoniland, Niger Delta, Nigeria: Lessons for Future Intervention. Ecological Restoration. 2016;**34**(2):245- 257. DOI: 0.3368/er.34.3.245

#### **Chapter 2**

## The Niger Delta Mangrove Ecosystem and Its Conservation Challenges

*Anthony E. Ogbeibu and Blessing J. Oribhabor*

#### **Abstract**

The Niger Delta region of Nigeria is a biodiversity hotspot, rich in fauna and flora, with robust ecological processes that drive the economy of the local communities. However, the area has not been formally recognized as a global biodiversity hotspot by international agencies such as the International Union for the Conservation of Nature (IUCN). The Niger Delta abounds in several species of mangroves, but the most dominant ones are the red (*Rhizophora racemosa*), black (*Laguncularia racemosa*), and white (*Avicennia germinans*) mangroves. The mangrove ecosystem in the Niger Delta is fast being replaced by Nipa palm (*Nypa fruticans*), yet no resultoriented action plan has been put in place to conserve the mangrove. The serious menace of oil pollution and overexploitation of fisheries and mangrove resources, in addition to environmental pressures, as well as poor recognition of brackish water bodies and aquaculture, causes serious danger to the sustainability of Nigeria's brackish water and the various fish resources, wildlife, and, inevitably, the coastal communities of the nation. This chapter provides essential information on the rich Niger Delta mangrove ecosystem and current conservation challenges and recommends strategies for sustainable management.

**Keywords:** Niger Delta, mangroves, biodiversity, water quality, conservation

#### **1. Introduction**

Nigeria is the most populous country in Africa. Since the attainment of independence in 1960, it has continuously grown in both size and influence, with an approximate population of 203 million people, accounting for 47% of the total West African population [1]. It hosts a variety of terrain and climate. The seven main ecological zones are the Mangrove Swamp and Coastal Vegetation, Freshwater Swamp Forest, Lowland Rain Forest, Derived Savanna, Guinea Savanna, Sudan Savanna, and Sahel Savanna [2]. The Niger Delta geographic basin is defined by the many tributaries of the lower River Niger, as it enters the Atlantic Ocean through its many tributaries and estuaries. It is a region with very high biodiversity as well as a dense human population. At the base of the Niger Delta, formed by a network of many creeks, is Africa's largest mangrove forest, the third largest in the world.

The Niger Delta is located on the Atlantic coast of Southern Nigeria, which extends between latitudes 4<sup>o</sup> 2<sup>0</sup> and 60 2<sup>0</sup> north of the equator and is 50 2<sup>0</sup> east of the Greenwich meridian [3, 4] and bordered by the Atlantic Ocean in the south, and Cameroon in the East. It occupies a surface area of about 112,110 km<sup>2</sup> . It represents about 12% of Nigeria's total surface area and is almost two-thirds of the entire population of Nigeria (i.e., 200 million). The region is made up of nine of Nigeria's constituent states (**Table 1**) [5]. The region has a yearly rainfall of 3000–4500 mm and an average temperature of 27°C. The wet season is relatively long, occurring from March to October, and the dry season from November to February [6, 7].

The Niger Delta floodplain occupies 7.5% of Nigeria's total land mass and is her largest wetland. It is the third largest drainage basin in Africa. The Delta's environment includes four ecological zones: coastal barrier islands, mangrove swamp forests, freshwater swamps, and lowland rainforests. This vastly well-endowed ecosystem contains one of the Earth's highest concentrations of biodiversity. Apart from supporting abundant flora and fauna, arable terrain that sustains a wide variety of crops, lumber, or agricultural trees, it also harbors more freshwater fish species than any other ecosystem in West Africa.

The biodiversity of the Niger Delta is of regional and global significance. Barrier islands, estuaries, mangroves, creeks, and freshwater swamps characterize the Niger Delta ecosystem. The Niger Delta region, considered a "*Biodiversity Hotspot*" by biodiversity experts, abounds in many locally and globally endangered species with robust ecological processes that drive the economy of the local communities.

Despite the importance of forest resources, there has been a rapid decrease recently due to the demand from an ever-increasing population. Drivers of forest loss in the different forest types are complex, including illegal logging from commercial loggers, due to high timber demand and communal logging of firewood for domestic cooking [8]. Mangrove ecosystems in the Niger Delta are fast being replaced by Nipa palm (*Nypa fruticans*). Yet no result-oriented action plan has been put in place to conserve the dwindling mangrove. The serious menace of oil pollution and overexploitation of fisheries and mangrove resources, in addition to other environmental pressures, as well as poor interest and recognition of brackish water bodies and aquaculture, cause serious danger to the sustainability of Nigeria's brackish water and


#### **Table 1.**

*Niger Delta states of Nigeria, their land areas, population, and capitals [5].*

the various fish resources, wildlife, and, inevitably, the coastal communities of the nation [9].

The importance of mangroves as nurseries has been one of the reasons to support their conservation and management [10]. Many African, Latin American, and Asian countries are now estimated to have lost at least 50% of their original mangrove area [11]. The current wave of global concern for the maintenance of essential ecological processes and life support systems, preservation of genetic diversity, and the sustainable utilization of species and ecosystems has led to the intensive survey of nature reserves for their ecological descriptions, biodiversity, and conservation status [12]. According to the International Union for the Conservation of Nature and Natural Resources (IUCN) report [13] on the global status of mangrove ecosystems, 18 countries have established mangrove reserves to safeguard the habitat and associated species. The mangrove zone of the Niger Delta is said to traverse parallel to the coast and reaches between 15 and 45 km inland. This deep belt of mangrove forest protects the freshwater wetlands in the Inner Delta [14].

The Niger Delta mangrove ecosystem, a fragile ecosystem increasingly being threatened by Nipa palm (*Nypa fruticans*) encroachment and industrial/oil pollution, is presently receiving urgent national and international attention for sustainable management and conservation. The problem is that the area has not been formally recognized as a global biodiversity hotspot by international agencies such as the IUCN. This Book Chapter provides essential information on the rich Niger Delta mangrove ecosystem and its conservation challenges and recommends strategies for sustainable management.

#### **2. Terrestrial ecosystems of Nigeria and mangrove ecosystems of the Niger Delta**

Nigeria has many regions with rich biodiversity serving as home to critical ecosystems. Among these regions are the Cross River basin rainforest, mountains along the Cameroon border with Nigeria, and the Niger Delta coastal creeks (**Figure 1**) [15, 16]. The Niger Delta mangrove is Africa's largest mangrove ecosystem and the world's third largest after India and Indonesia, the third largest drainage basin in Africa, and Africa's largest river delta [17, 18].

The coastal region of Nigeria extends from Benin Republic/Nigeria border in the west to the Cameroun/Nigeria border in the east, a distance of 800 km but with a coastline of 853 km [19]. This coastline has interfered with a series of estuaries that empty into the extensive lagoon system in Lagos and Ondo State. At least twenty-two (22) estuaries exist between the Benin River in Delta State coastal region and the Cross River in Akwa Ibom State. In the Delta and River State areas, the estuaries join with tributaries and distributaries of the lower Niger River/Benue system to form an anastomosing system of fresh and brackish water creeks, backwaters, and flood plains in what is better described as the Niger Delta basin swamps [20]. The creeks, floodplains, lagoons, and rivers in Lagos State account for approximately 22% of the 790 km<sup>2</sup> land mass [21].

The brackish water sector consists of estuaries, beach ridges, intertidal mangrove swamps, intersecting rivers, and winding saline creeks. The exact area of the brackish water for the entire Nigerian coastline is unknown except for the Niger Delta portion, the area of which has been estimated [22] and includes the constant saline creeks that form an area of about 1000 km<sup>2</sup> and the intertidal mangrove swamps consisting an

**Figure 1.** *Nigeria's terrestrial ecoregions [15].*

area of about 5048 km<sup>2</sup> . In addition, there are intersecting rivers and estuaries plus beach ridges with an area of about 679 km<sup>2</sup> and 688 km<sup>2</sup> , respectively. The total brackish water area of the Niger Delta is therefore approximately 7415 km<sup>2</sup> . The inland area of the mangrove swamp fairly delimits the brackish water area. The brackish water region of Nigeria's coastal zone between the Benin River and Cross River has been adequately delineated [23].

Mangrove forests could be cleared for aquaculture ponds, salt pans, agricultural use, including rice fields, airport and road construction, port and industrial development, resettlement, and village development [24]. They are, however, important factors in stabilizing the shoreline (http://www.panda.org). Some endangered and potentially vulnerable species are endemic in this area. The mangrove swamps and adjoining freshwater swamps in the Niger Delta provide critical habitats for many endangered animal species, important wildlife, and migratory and resident aquatic reptiles, birds, and mammals. These include crocodiles, Nile monitor lizards, parrots, duikers and antelopes, monkeys, bush pigs, bush cow or buffalos, sitatungas, hippopotamus, diving pelicans, and deep swimming shags [25]. The subtidal prop root of mangrove habitats serves as nurseries for fishes of economic importance [26]. The interest in protecting mangroves worldwide is due to their purported importance to fisheries and a number of rare and endangered species [27]. However, because the same mangrove species can often occur under marine, estuarine, and freshwater conditions, a wide variety of fish assemblages can be found among their inundated "mangrove habitats." As such, mangrove habitats likely play a variety of roles in the lives of associated fishes, feeding areas for some species or life stages, daytime refugia for others, and nursery and/or nesting areas for yet more. Mangroves of the Atlantic

coast of Africa, including the Niger Delta, on account of their gentle gradient of sediment, are sensitive/fragile [28]. The rich biodiversity and high aquatic productivity of the West African coastal waters are constantly undergoing bio-modification due to the adverse impact of human activities [29].

#### **2.1 Mangrove flora of the Niger Delta**

The most symbolic mangrove species in Nigeria consists of six species in three families, namely: Rhizophoraceae (*Rhizophora racemosa, R. harrisonii, and R. mangle*), Avicenniaceae (*Avicennia africana*), and Combretaceae (*Laguncularia racemosa* and *Conocarpus erectus*). In terms of biodiversity, the Niger Delta mangrove ecosystem is one of the richest wetlands globally by researchers.

There are several species of mangroves in the Niger Delta, with the most dominant ones being red (*Rhizophora racemosa*), black (*Laguncularia racemosa*), and white (*Avicennia germinans*) mangroves. They provide highly productive habitats and ecological niches for reptiles, monkeys, birds, fishes, shrimps, mollusks, and other wildlife species, and a number of other ecological services [30]. Also prominent but less studied and uncommon around core mangrove forests are Button wood mangroves (*Conocarpus erectus*). They are common in inland sandy soil areas [5]. The following eight true West African mangrove species are found in Nigeria, particularly in the Niger Delta region: *Avicennia germinans*, *Rhizophora mangle*, *Rhizophora racemosa*, *Rhizophora harrisonii*, *Laguncularia racemosa*, *Conocarpus erectus*, *Nypa fruticans,* and *Acrostichum aureum*. The Families Rhizoporaceae, Avicenniaceae, and Combretaceae, such as *Rhizophora racemosa*, *Rhizophora harrisonii*, *Rhizophora mangle*, *Avicennia africana* (White mangrove), *Laguncularia racemosa*, and *Conocarpus erectus* and a few other stunted shrubs and woody species are the most dominant plant species.

Most locations in the Niger Delta have similar mangrove species composition [5]. The floristic composition of the plants and family distribution in the Mangrove Swamp Forest of Anantigha in Calabar South Local Government Area (LGA), Cross River State, Nigeria, is shown in **Table 2** [30]. The plant population consisted of *Rhizophora racemosa*, *Nypa fruticans*, *Avicennia germinans*, *Acrostichum aureum*, *Drepanocarpus lanatus*, *Lagunicularia racemosa*, *Hibiscus tiliaceus*,*Thespesia populnea*, *Pandanus candelabrum*, *Carapa procera*, *Raphia hookeri*, *Conocarpus erectus,* and *Chrysobalanus spp.* [30]. The most abundant species in the area are *Rhizophora racemosa*, *Nypa fruticans*, *Avicennia germinans,* and *Acrostichum aureum*. *Rhizophora racemosa* had the highest species importance value (SIV), followed by *Nypa fruticans*, an exotic palm that encroaches on the mangrove and dominates the indigenous oil palm, *Elaeis guineensis* [30]. For the grass species, *Dalbergia ecastaphyllum* is reported to have the highest diversity (**Table 3**). Species distribution from seaward to landward areas indicates that core mangrove species were found on the seaward side, whereas the non-mangrove species were found in the landward direction [5].

A related study documented the common plant species in Tunu and Kanbo in South Forcados of the Niger Delta ecosystem. The predominant vegetation type within the Tunu/Kanbo field is the mangrove swamp forest type, attested to by the floral composition (**Table 3**) [31].

The dominant plant with the highest frequency of occurrence is the dwarf red mangrove, *Rhizophora mangle*. The tall red mangrove *R. racemosa* was confined to the edge of the creeks and rivers. Herbaceous grasses, fern, and sedges such as *Acrostichum aureum, Paspalum vaginatum,* and *Fimbristylis spp.* occurred on the forest floor below the mangrove canopy. Epiphytes were abundant on the tree trunks. The


**Table 2.**

*Plants found in Anantigha mangrove swamp forest with their species density, relative density, and species importance value (SIV) [30].*

commonest species include *Bulbophyllum oreonastes* and the moss *Ocoblepharum sp.* The mangroves are admirably adapted to the brackish environment. They have stilt roots that are covered with lenticels. The latter serves as passages for gaseous exchange. Oxygen and carbon dioxide are channeled through these structures. The superficial roots are thus sensitive. The trees can easily die if the ventilating organs (lenticels) are blocked. Mangroves grow best where there is regular tidal flushing. Changes in hydrology resulting from dredging or blockage of natural tidal channels can severely reduce their growth and may result in death (**Figure 2**).

Some parts of the barrier forests, common along the Nigerian shoreline, occur within the field. They appear as small forest islands within the "sea" of mangroves. Typical plants within these forests include the breadfruit tree (*Artocarpus communis*), Abura (*Hallea ciliata*), *Allanblackia floribunda,* Fig tree (*Ficus trichopoda*)*, Uapaca heudelottii*, and S*ymphonia globulifera.* These species are typical of freshwater swamp forest. These forest islands within the sea of mangrove forests are analogous to oasis within the desert. They are the only places the coastal communities get their potable water from. They are thus sensitive ecosystems with a unique function. Salt-water intrusion can easily kill the vegetation within these islands as the plants inhabiting them are not salt tolerant. The coastal communities also utilize the forest islands for agricultural purposes. Breadfruit and plantain are cultivated within these forests. The forests thus allow them to get staple food in an otherwise nonarable environment (**Table 4**).

Indices based on the proportional abundance of species provide a simplified approach to diversity measurement. These *heterogeneity indices* take into account both evenness and species richness to produce a single value, the Shannon Index of diversity (H1 ). The diversity was analyzed using the Shannon diversity index (H<sup>1</sup> ), Margalef index of species richness (d), Equitability or Evenness index (J), and Dominance index (D).

*The Niger Delta Mangrove Ecosystem and Its Conservation Challenges DOI: http://dx.doi.org/10.5772/intechopen.112543*



**Table 3.**

*Plant species list in Tunu field in south Forcados [31].*

**Figure 2.** *Mangrove vegetation in Tunu field (Note:* Nymphaea lotus *floating around the mangrove roots) [31].*

The Shannon diversity index is a measure of community stability or ecological robustness that makes any community able to withstand external perturbation with minimal disruption. Diversity values of <1.00 indicate heavily polluted, 1–3 indicate moderate pollution, while values > 3 indicate clean and unperturbed habitats. The equitability index measures how evenly distributed the individuals are among the species, while the Dominance index is the opposite of equitability, that is, when individuals are not evenly distributed among the species, but rather, only a few species have a concentrated number of individuals. The environment belongs to the category of moderate perturbation or pollution.

#### **2.2 Mangrove fauna of the Niger Delta**

The highest concentration of aquatic organisms in Africa is found in Nigeria's Niger Delta mangrove forest zones (**Figure 3**). The species include from plankton (phytoplankton and zooplankton), aquatic invertebrates (bivalves, crabs, mussels, periwinkles, hermit crabs, etc.), and land insects (beetles, butterflies, mosquitoes, ants, and termites) to vertebrates (monkeys, manatee, pygmy hippopotamus, python, etc.) (**Figures 4** and **5**) [32]. The enigma is that the region is yet to be formally recognized as a global biodiversity hotspot by international agencies like the International Union for the Conservation of Nature (IUCN). Biodiversity hotspots in Africa have commonly grouped together without recognizing the rich biodiversity across different locations. For example, the entire forest biodiversity in West Africa was grouped as "West African forests" [34], whereas individual countries in this region have a diverse and rich supply of biodiversity.

The Nigerian mangrove swamps harbor a great diversity of macro in- and epi-faun of which crabs and mollusks form the great majority in terms of biomass. The fauna


*The Niger Delta Mangrove Ecosystem and Its Conservation Challenges DOI: http://dx.doi.org/10.5772/intechopen.112543*

#### **Table 4.**

*Abundance and diversity of weed species commonly found around mangrove forests in the Niger Delta, Nigeria [5].*

faces severe water and salt balance, siltation, desiccation, oxygen availability, weight, and temperature limitations, especially when attempting to invade the adjacent land. Presently, few quantitative estimates of Niger Delta mangrove swamp fauna exist, perhaps due to the difficulty of sampling among thickets of mangroves, deep mud banks, and semi-stagnant lagoons, in addition to the difficulty in obtaining reliable estimates of fauna, which spend much of their time in burrows or very active when on the ground. In many cases, the seasonal occurrence and distribution of most macrofauna in the swamp are related to the characteristic fluctuations in environmental parameters associated with the dry and wet seasons as well as stress from anthropogenic activities. Besides, the influence of substratum on faunal species distribution in the Nigerian mangrove swamp of Nigeria has been reported [35].

There are presently few quantitative estimates of Niger Delta mangrove swamp fauna in the literature. Studies of Buguma Creek, a mangrove creek in Rivers State, Nigeria, resulted in the documentation of Zooplankton made up of 37 taxa in the Phyla Arthropoda, which was the most dominant: Coelenterata (Cnidaria); Ctenophora; Annelida; Chaetognatha; and Chordata. Macrobenthic invertebrates comprised 68 taxa in the Phyla Arthropoda and Annelida (the most dominant), Nematoda, and Mollusca. Fish species made up of 20 taxa in the families Sciaenidae (the most dominant), Elopidae, Ariidae, Gobiidae, Serranidae, Carangidae, Lutjanidae, Haemulidae, Monodactylidae, Sphyraenidae, Polynemidae, Trichiuridae, Cynoglossidae, and

#### **Figure 3.**

*Some species found within the Niger Delta mangrove forest: (A)* Senilia senilis*, Anadara; (B)* Crassostrea gasar*, oyster; (C)* Tympanotonus fuscatus*, periwinkle; and (D)* Uca tangeri*, male crab [32].*

#### **Figure 4.**

*Heslops pygmy hippo,* Hexaproton *(syn-*Choeropsis*),* liberiensis heslopi.

Dasyatidae (these excluded members of the family Cichlidae (*Tilapia guineensis* and *Sarotherodon melanotheron*), Mugilidae (*Liza facipinnis, Mugilcephalus,* and *Mugil curema*), and *Sardinella maderensis* (Clupeidae), which the baited hooks and lines could not catch) [9].

*The Niger Delta Mangrove Ecosystem and Its Conservation Challenges DOI: http://dx.doi.org/10.5772/intechopen.112543*

**Figure 5.** *Protected python seen close to a residential building in Brass Island [33].*

**Table 5** shows the macrofaunal distribution and abundances in a study area that extends from the Cross River Estuary (which is relatively less perturbed and therefore used as a control swamp) to Takwa Bay in Lagos, approximately 870 km stretch and encompassing Imo River, Bonny River, Brass River, and Forcados and Escravos river estuaries. The preponderance of polychaetes in the upper ranks can be seen with *Capitella capitata, Chaetozone setosa,* and *Magelona filiformis* dominating. *Echinocardium* was ranked 65th with a density of 5/m<sup>2</sup> . The coefficient of variation for each species is also presented in the table. This index (standard deviation ÷ mean density) indicates the spatial evenness in the abundance of the species, with numbers much less than one indicative of a uniform distribution [35].



**Table 5.**

*Rank and abundance of dominant macrobenthic Fauna in the Niger Delta mangrove ecosystem during 1985– 2005 [35].*

#### **3. Ecosystem services of Niger Delta mangroves**

The four categories of ecosystem services that have been identified are: regulating services, provisioning services, cultural services, and supporting services.

**Figure 6.** *Prop roots providing attachment sites for oyster* Crassostrea gazar *[18].*

#### *The Niger Delta Mangrove Ecosystem and Its Conservation Challenges DOI: http://dx.doi.org/10.5772/intechopen.112543*

The Niger Delta mangroves perform almost all the services listed above, such as from atmospheric and climate regulation, flood and erosion control, wood and timber for cooking fuel and construction to benefits such as esthetic value, sacred sites, traditional medicine, and supporting services such as nutrient cycling and habitat for fish nursery [18].

In addition to the aforementioned ecosystem services, the Niger Delta mangrove provides niche types that support the existence of a diverse fauna of all developmental stages. Several burrows contain diverse species of polychaetes, crabs, shrimps, and fishes supported by the rich food sources peculiar to the mangrove. Stilt roots of Mangrove plants provide substrate for the attachment of edible epifaunal organisms such as the oysters *Crassostrea* spp*.* (**Figure 6**) [18].

The mangrove trees conserve water resources and serve as windbreaks in many communities. Specifically, in the Niger Delta, other uses of mangroves by the indigenous people include building materials, food baskets, fishing tools, and so on [5].

#### **4. Threats to mangroves of the Niger Delta**

The mangrove forests of the Niger Delta are undergoing gradual but steady loss, resulting from uncontrolled deforestation for sand dredging and canalization. The mangrove forest is also cut to recover stems, which are used in producing firewood and wood for the construction of houses. Numerous oil and gas exploratory activities all over the Niger Delta area also open up the forests to further exploitation of resources [34]. Invasion by foreign species, such as nipa palms (*Nypa fruticans*), also threatens the existence of the rich indigenous mangrove species. Habitat loss is one of the three factors responsible for the recent extinction of species. Overexploitation and the introduction of exotic species are the other two. The consequence of the loss of mangrove habitat is the loss of ecosystem services it renders to society [34].

Oil exploration and extraction activities constitute Nigeria's most severe threat to the mangrove forest ecosystem. Nigeria's Oil Industry is located mostly in the mangrove forest ecosystem. The activities of various oil exploration companies have resulted in fragmentation, deforestation, and degradation of the mangrove forest ecosystem. The Nigerian Oil Industry has deforested mangrove ecological zones for drilling purposes and further deteriorated the health of the surrounding mangrove areas through oil spillages. Oil spill kills plants and animals in the estuarine zone, endangers fish hatcheries in coastal waters, and contaminates the flesh of commercially valuable fish. The oil that settles on beaches decimates the inhabiting organisms, while that settling on the ocean floor smothers and kills benthic (bottom-dwelling) organisms like crabs and disrupt major food chains. Oil also submerges birds, impairing their flight or reducing the insulating property of their feathers [36].

#### **5. Management and conservation of the Niger Delta mangrove ecosystem**

#### **5.1 Mangrove forests**

The Niger Delta mangrove forest requires urgent protection due to the adverse impact of anthropogenic activities resulting in the decimation of their populations in many regions. Incessant destruction of the mangrove forest will result in the local extinction of these species. Therefore, to reduce the anthropogenic impact on

mangroves, there is an urgent need to establish protection and restrict human entry into the forest. Based on the importance of the biodiversity hotspots to the environment, it is pertinent to protect them for future generations [34].

In the past, the conservation of biodiversity hotspots was mainly focused on species richness, but now it considers ecosystem integrity, water quality, climate impacts, unique adaptations, ecosystem services, intact fauna and flora, specialized/ unique habitat, and ecological processes.

Mangrove forest protection should follow the principles of reserve design, which include: the protection of entire habitats (because the more protected habitat, the better it is); avoidance of reserve fragmentation by anthropogenic activities such as the construction of highways through mangrove forests; establishment of the clumped reserve, which is far better than linear, for easy migration of species within the mangrove forests; and establishment of a circular reserve to minimize edge effects.

A damaged mangrove ecosystem could also be repaired through ecological restoration, the process of repairing damage caused by humans to the diversity, and dynamics of the indigenous ecosystem. This process includes erosion control, reforestation, removal of non-native species such as *N. fruticans* and weeds, revegetation of disturbed areas, daylighting streams, reintroduction of native species, and range improvement for targeted species. Hydrological links to natural restoration sites are also significant in allowing saline water inflow and mangrove seeds. The inflow of water also cleans the site from oil spillage and other pollutants [37].

There is an urgent need for a long-term management plan for the sustainable use of mangrove ecosystems. Monitoring, research, and evaluation constitute vital components of a successful conservation strategy for natural, managed, and man-made mangrove forests.

Conservation of existing mangrove forests is often more effective than planting new forests. When a decision for planting has been made, there is a need to emphasize the careful selection of appropriate sites and species and an ecosystem-based approach to mangrove planting and management, which utilizes and supports natural regeneration and other natural processes. In the process of any rehabilitation intervention work, planting should be done only when absolutely necessary. Local communities must be engaged in mangrove management to effectively maintain and enhance the protective function of the mangrove forest while providing a livelihood for local people and contributing to better assessment and governance of natural resources. Continuous assessment of mangrove forest status through research, economic assessment, and valuation is important for better conservation, planning, and management [38].

As a result of the current threat to forest resources, forest reserves have been created by the Nigerian government in the swamp/mangrove ecosystems of some Niger Delta States (**Table 6**).

#### **5.2 Game reserves/wildlife sanctuary**

Most of the Protected Areas are Forest Reserves. A few have been designated at one time or the other Game reserves (**Table 7**). None has the legal instrument for the designation as Game Reserve. They were recognized as having rich faunal compliments but never transited legally into Game Reserves.

A Preliminary Assessment of the Context for Reducing Emissions from Deforestation and Forest Degradation (REDD) in Nigeria commissioned by the Federal Ministry of Environment, the Cross River State's Forestry Commission, and UNDP Strict Nature Reserve (SNR) remarked that:

*The Niger Delta Mangrove Ecosystem and Its Conservation Challenges DOI: http://dx.doi.org/10.5772/intechopen.112543*


#### **Table 6.**

*Forest reserves according to vegetation type.*


#### **Table 7.**

*Existing and proposed game reserves/wildlife sanctuaries in the zone.*

These former forest reserves have been specifically designated for conservation, management, and propagation of wild animals in addition to the protection and management of the critical habitats on which they depend. In practice, almost all the game reserves in the country (except for Yankari, which was formerly a National Park) are highly degraded due to poor management; they best be described as "paper" game reserves.

#### **6. Surface water and sediment quality in mangrove ecosystem**

The Escravos Beach within the Niger Delta Mangrove was used as a case study [39]. The mean values of all physicochemical parameters investigated during the wet and dry seasons are summarized in **Table 8**. The water bodies sampled in the location had slightly alkaline pH in the wet season and slightly acidic in the dry season, high conductivity and dissolved solids, slightly high turbidity and color, and moderate dissolved oxygen and Biochemical Oxygen Demand (BOD) level. The water was brackish with higher salinity values in the dry than in the wet season. The cations were dominated by sodium and potassium, followed by calcium, truly reflecting the brackish nature of the water body. The nutrient level was higher in the wet than the dry season, probably due to the influx of allochthonous organic materials and ions into the water body. The parameters were all within the normal range stipulated by the Department of Petroleum Resources (DPR) (now called Upstream Petroleum Regulatory Commission, NUPRC) and Federal Ministry of Environment (FMEnv), except in a few cases such as turbidity, color, and total dissolved solids (TDS), where the limits were exceeded. The turbidity and color were expected to be higher in the wet season due to the input of organic materials from the terrestrial environment. The high total dissolved solids followed the electrical conductivity pattern, which was greatly influenced by the high salt content. The hydrocarbon pollution indicators, like the total petroleum hydrocarbons (TPH), polyaromatic hydrocarbons (PAH), BTEX (benzene, toluene, ethylbenzene, and xylene), and phenols, were all very low in concentrations and fell within the recommended limits by DPR and FMEnv. The low concentrations of heavy metals indicate no serious pollution from petroleum and other anthropogenic activities at the study location.

Microorganisms are responsible for forming various sediment and mineral deposits and dominating secondary waste treatment. Microorganisms such as bacteria and fungi act as living catalysts enabling numerous chemical processes in water and soil. Most significant chemical reactions in water, especially those involving organic matter and oxidation-reduction processes, occur through bacterial intermediaries.

The bacterial and fungal counts of the surface water samples from the study area were low. The total heterotrophic bacteria counts ranged between 0.7 103 cfu/ml and 2.4 <sup>10</sup><sup>3</sup> cfu/ml. The total heterotrophic fungal counts ranged from nil to 1.0 <sup>10</sup><sup>3</sup> cfu/ml. The hydrocarbon-utilizing bacterial and fungal counts were absent for most surface water samples.

The summary of sediment quality parameters is presented in **Table 9**. The sediment was moderately acidic (<7.0). The nutrient concentrations were higher in the sediment than in the surface water. The earth metals (cations) were low in concentration, with calcium dominating in the wet season. The heavy metals were low in concentration in all the stations. The higher sediment concentration is expected since the bottom sediment typically serves as a reservoir for heavy metals in the water. The recorded values are all below the intervention values. Concentrations above the intervention values corresponded to severe contamination. The target values indicated the soil quality levels ultimately aimed for [39].

There was no adverse effect of anthropogenic activities on the water and sediment of the study area.

The microbial load in the sediment was low for both the heterotrophic and the hydrocarbon-utilizing bacteria and fungi, indicating no serious hydrocarbon contamination.


#### *The Niger Delta Mangrove Ecosystem and Its Conservation Challenges DOI: http://dx.doi.org/10.5772/intechopen.112543*


#### **Table 8.**

*Summary of physicochemical characteristics of surface waters in the Escravos Beach study area [39].*



*The Niger Delta Mangrove Ecosystem and Its Conservation Challenges DOI: http://dx.doi.org/10.5772/intechopen.112543*

**Table 9.**

*Comparison of the characteristics of sediment samples from the study area during the dry and wet seasons [39].*

The mean values of physical and chemical parameters for surface water and sediment are true reflections of the typical mangrove quality unless there is gross contamination from oil exploration and production activities by oil companies.

#### **7. Conclusion**

The coastal areas of West Africa contain some of the world's richest ecosystems, including extensive mangrove forests, lagoons, and estuaries that support wide biodiversity with significant economic benefits to the coastal populations. Wetlands are important buffers for adjacent marine ecosystems, trapping sediments, nutrients, and many anthropogenic chemical contaminants. Mangrove ecosystems, for instance, serve as sinks for heavy metals because mangrove sediments' physical and chemical properties allow them to sequester large quantities of metals. There is wide variability in the ability of mangrove plants to absorb heavy metals because the sediment conditions vary widely. Different species of mangrove trees have different

sediment-trapping root systems adapted to combating the anoxic conditions in the peat, including the pores or lenticels on the prop roots of *Rhizophora* spp. or on the pneumatophores (peg roots) of *Avecinnia germinans.*

Ineffective planning and management of coastal zone, the absence of environmental impact assessment, inadequate incorporation of environmental issues into feasibility projects, population pressures, as well as economic expansion are threatening the integrity of natural ecosystems. The main types of human activities that damage coastal ecosystems are (1) overexploitation, (2) physical alterations and habitat loss, (3) pollution, (4) introduction of alien species, and (5) global climatic change. In many coastal areas of Africa, vast areas of coastal wetlands and beaches have been cleared to make way for coastal development, industrialization, aquaculture, and agriculture. It destroys rich mangrove and estuarine fisheries and many commercially valuable species that depend on these coastal habitats as nursery grounds. Continuous examination of the relationship between man, the coastal environment, and its resources (human impacts) is clearly needed to avoid the risk of depletion and damage.

The rich ecosystem services of the Niger Delta mangrove, which is currently threatened by anthropogenic influence, require urgent protection and conservation attention. There is an urgent need for policymakers, development planners, and other stakeholders to arouse public consciousness for the restoration, rehabilitation, and conservation of mangrove ecosystems in Nigeria to achieve sustainable utilization.

#### **Acknowledgements**

This contribution contains information gathered from our Ph.D. research and environmental consultancy reports carried out for some oil and gas industries operating in the Niger Delta region of Nigeria. This is in addition to the cited literature. The authors wish to particularly acknowledge MacGill Engineering and Technical Services Limited, an environmental consultancy outfit that funded the Environmental Impact Assessment studies for South Forcados Development Project and the Escravos Beach Project carried out for SPDC.

*The Niger Delta Mangrove Ecosystem and Its Conservation Challenges DOI: http://dx.doi.org/10.5772/intechopen.112543*

#### **Author details**

Anthony E. Ogbeibu<sup>1</sup> \* and Blessing J. Oribhabor<sup>2</sup>

1 Faculty of Life Sciences, Department of Animal and Environmental Biology, University of Benin, Benin City, Nigeria

2 Department of Fisheries and Aquatic Environmental Management, University of Uyo, Uyo, Akwa Ibom State, Nigeria

\*Address all correspondence to: ogbeibu.anthony@uniben.edu

© 2023 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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#### **Chapter 3**
