**1. Introduction**

Mangroves are shrubs or small trees that inhabit the interface between the land and the sea. They are habitat specialists that grow along coastal regions. They grow in swampy soil that is continuously wet from year to year because of the action of tides and heavy rainfall. Mangroves are found in tropical areas with high solar radiation and precipitation [1]. The mangroves of the Niger Delta are the third largest in the world and the largest in Africa [2]. It is a biodiversity hot spot, and is found in the tropics close to the equator where rainfall persists all year round. The climate is hot and facilitates the proliferation of living organisms from microbes to vertebrates through series of speciation and evolutionary

events. Biodiversity hot spots are important zones because they contain 25% of all terrestrial species. Hot spots are small areas on the map (i.e., about 2%), but wield so much ecological influence on the surface of the earth. They contain disproportionately large numbers of species on earth. Tropical forest has the largest number of species in the world. It has a lot of taxonomic diversity, which includes plankton, macrophytes, arthropods, fungi, protists, mollusks, crabs, vertebrates including birds and mammals. Mangrove forest is the most dominant amongst the plants found in the coastal region of the Niger Delta area. The reasons for high species diversity in mangrove forests of the Niger Delta are because of high reproduction and productivity [3]. The tropics are areas that have high speciation and less species extinction. Secondly, the stability hypothesis postulates that the tropics have been more stable than present in the last 1000 years and will remain so for a long period of time. It is stable with respect to the abiotic conditions that prevail in the area. Similarly, the equator has been stable with respect to global warming and cooling with lower extinction rate recorded over the years. Furthermore, intense solar radiation had resulted in an increase in overall productivity resulting in high biodiversity turnover. The tilt of the earth also affects how the photon of sun hits the earth. The sun position right overhead the equator serves as a major source of energy. Plants capture solar energy, which they convert to food for other organisms in the ecosystem. The captured energy is converted into biomass, which is transferred to the production of more resources. This is exemplified in the high productivity of mangrove forests recorded in the Niger Delta [3]. Increased litter fall facilitates high decomposition [1] and makes food available for different species of organisms in the food chain. The tropical environment is highly specialized. High specialization and speciation lead to high biodiversity. But the problem of mangroves globally is the gradual loss of their habitat due to anthropogenic activities [4]. This study showed that 35% area of global mangrove forest had been lost as a result of some human activities such as shrimp culture, forest use, fish culture, diversion of freshwater, land reclamation, herbicides, agriculture, salt ponds and coastal developments. In Africa coastal development is a major factor of habitat loss [4]. Although, other studies had revealed that Nigeria has one of the least carbon CO2 emissions from soil as a result of mangrove losses [5]. Similarly, previous studies have shown that habitat conversion far exceeds habitat protection by a ratio of 8:1 globally [6].

### **1.1 Mangrove forest resource in Nigeria**

A forest is an ecosystem, which is dominated by trees. Forest produces timber and non-timber products. Non-timber forest includes anything other than timber. Forest products are all renewable and can be sustainably managed. More often than not mangrove forest is looked at from the economic resource angle. This is because they are the sources of revenues such as wood, firewood, latex, dyes, thatches, bamboo, reptiles, insects, roots, shoots, stems, flowers, honey resins, gum, silk, fabrics, rope, animal oil, cosmetics, water from streams and lakes. The value of these resources is often difficult to quantify. We also have nature reserves and recreational activities.

Nigeria has a wide and diverse range of habitats from arid zones in the north to the swampy wetlands in the south. Many forest types (tropical rainforest, Sahel savanna, Guinea savanna, Sudan savanna, Montane savanna, etc.) are associated with these zones and have an array of plant and animals species. Some of these biodiversity include:

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**2.1 Habitat loss**

*Mangrove Habitat Loss and the Need for the Establishment of Conservation and Protected Areas…*

1.**Plants**: There are over 4,600 plant species in Nigeria. Out of these figures 205 plants species are endemic. But they are under the threat of extinction through

2.**Mammals**: There are about 274 species of mammals, which is the highest number in Africa. Two endemic species are the white coated guenon and the red

3.**Birds**: Nigeria has about 839 species of birds with two as endemic. They are Anambra waxbill and Ibadan malimbe. All birds of prey are considered threat-

4.**Reptiles**: They are about 56 species of forest snakes in Nigeria. We also have 56 savanna snake species. Crocodiles, pythons, monitor lizards and turtles, which

5.**Amphibians**: There are about 19 recovered species of amphibians in Nigeria, 5 of which are endemic to Nigeria and Cameroun, and 3 are under threat of

6.**Invertebrates**: The giant swallow tail and generally other lepidopteran species are under threat in Nigeria due to pollution from oil and gas exploration. Only about 1.7% of Nigeria land is included within protected area as compared with the large landmass. Even the protected areas are being degraded

There is a gradual but steady loss of mangrove forests in the Niger Delta due to uncontrolled deforestation for the purpose of sand dredging and canalization (**Figure 1**). Mangrove forest is also cut to recover stems, which are used in the production of firewood and wood for the construction of houses. Similarly, numerous oil and gas exploratory activities all over the Niger Delta area open up the forests to further exploitation of resources and invasion by foreign species such as nypa palms (*Nypa fruticans*) [7]. Habitat loss is amongst the three important factors that are responsible for recent species extinction. The other two are overexploitation and the introduction of exotic species [8]. The implication of the loss of mangrove habitat is

Habitat loss leads to extinction because species are adapted to a particular habitat type. For instance, mangroves are habitat specialist that survives in swampy wetland soil, therefore, when they are removed from their native environment and taken to other environment they do not survive. There is also a relationship between the numbers of habitats and the species present. This is because the larger the habitat size the higher the number of species, and the smaller the habitat size the fewer the number of species present. There are many ways humans cause the loss or conversion of mangrove forests, these include tree cutting for production of firewood, agriculture (e.g., fish farming or rice paddies), construction of houses and hydrocarbon pollution from oil and gas exploration activities. Currently, there are numerous

by poaching, illegal logging and infrastructural development.

the loss of ecosystem services it renders to the society [9].

*DOI: http://dx.doi.org/10.5772/intechopen.89623*

tailed monkey. They are also endangered.

extinction from habitat destruction.

**2. Habitat loss and conversion**

due to overexploitation.

ened in Nigeria

are under threat.

*Mangrove Habitat Loss and the Need for the Establishment of Conservation and Protected Areas… DOI: http://dx.doi.org/10.5772/intechopen.89623*

