4. Impact of landscape reclamation on marine ecosystem

The marine coastal ecosystem is made up of different zones. The uppermost layer or photic zone is 10 m of water and absorbs 80% of solar energy, which carries out primary productivity. The warm shallow waters of the continental shelves are most biologically productive and support the greatest species diversity. Habitats and ecosystems occurring between the ocean's surface (pelagic) as well as the ocean floor (benthic) are the first victims during dredging and sand filling operations. This is because the organisms that reside in these areas are wiped out during the first phase of reclamation.

Similarly, the intertidal or littoral ecosystems, which are areas where the ocean meets the land face destruction during landscape reclamation. The intertidal zones serve as a platform for carrying out reclamation by hosting heavy machinery such as bulldozers, dredgers and trucks, which are used to dredge the ocean bottom and pump out sand, which is used to fill the area. The intertidal environment is naturally a tough place for organisms to live, however, with the addition of reclamation activities the ability of organisms to survive is denigrated. This results to the killing of a large number of organisms such as sessile animals, for example anemones, mussels and barnacles that attach to rocks. There are also some burrowing organisms that dig into shore sand. Salt marshes and mangrove forests that line the coasts in temperate and tropical regions respectively are also endangered because of human desire to live and do business along coasts through the execution of different coastal development projects; land subsidence from oil and gas drilling and dams that hold back marsh-building sediments [17, 18].

Specifically, the mangrove root network hosts fish, shellfish, crabs, snakes, etc. In the same vein, birds feed and nest in the dense foliage. Mangroves provide various ecosystem services such as food, medicine, tools and construction materials. Globally, half of the world mangroves have been destroyed [16] as people have reclaimed those areas as a result of coastal development. Shrimp farming in particular has resulted to the conversion of large areas of mangroves. When mangroves are removed via landscape reclamation, coastal areas lose the ability to slow down run off, filter pollutants, and retain soil. As a result, offshore systems such as coral reefs and eel grass beds are readily degraded. Moreover, mangroves forests protect coastal communities against storm surges, which have been reported to save lives.

### 5. The role of human ecology in land reclamation

People participation is very important in landscape reclamation because it would provide a consensus view on land use to the host community [19]. Five ways human ecology influence reclamation of coastal environment include:


reckless and indiscriminate hunting in opened forest reduces population and thus

This could lead to the death of soil dwelling organisms. Changes in river channel via canalization or dredging changes the river system by increasing the length and breadth of the river which affects the flow dynamics and hydrology of the river [3]. This situation affects the fish survival and population. Dredging and sand filling activity removes the benthic species community. It also deepens the sea bed, which affects the water level. Decrease in water level affect intertidal level especially when areas along the shore receive no water supply and become dry. This leads to the death or migration of amphibious species along the coast. The dehydration of the intertidal areas cuts off dissolved oxygen and food supply to aquatic species.

This could lead to the reduction in species composition and diversity of aquatic

This includes zooplankton, phytoplankton, benthic organisms and fisheries. It also affects soil-dwelling organisms from adverse impact on water and soil quality. The felling of trees and the uprooting of their stumps leads to soil fragmentation. Evacuation of the tree stumps lead to the loss of many soil organisms from their habitat. Sand filling of the coasts lead to the burial of millions of species. Loss of trees leads to increased soil erosion and increased sedimentation of river.

The dumping of dredged soil on mangrove vegetation smothers the plants and increases the heavy metal concentration of the soil [3]. This affects the survival of soil-dwelling organisms by increasing the acidity and alkalinity of the soil. Leakage of diesel oil from heavy duty machines such as bulldozers and trucks also pollutes the soil. Similarly, the contamination of surface and ground water with used engine oil can pollute the ground water aquifer, thus affecting neighboring community that

The bulldozers that fall the trees and the trucks that evacuate the logs all gener-

This could lead to the contamination of soil surface and ground water, disrup-

ate smoke which pollutes the surrounding air leading to poor air quality, and resulting in acid rain. This leads to the impairment of the health of aquatic and

tion of fishing activities and decrease in aesthetic value of the environment.

resources. It could also lead to fish kills and smothering of aquatic organisms. Increased turbidity leads to the blockage of light beyond water surface, thus hampering photosynthetic activities below the water surface such as the benthic region.

3.1.7 Ground water/soil quality could be impaired by leachates from generated

reduces species diversity, which may lead to extinction of some species.

Landscape Reclamation - Rising From What's Left

3.1.4 Changes in topography of sand filled area/river bed and dredged areas

3.1.5 Increased turbidity

3.1.6 Disturbance of aquatic life

dredged soil

drink water from bore hole and hand dug well.

terrestrial organisms around the reclaimed area.

3.1.8 Impairment of environmental quality

3.1.9 Improper disposal of solid waste

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6.1 Case study: seedling recruitment experiment

DOI: http://dx.doi.org/10.5772/intechopen.82053

Areas that have mangrove vegetation before can be restored through the

The Impact of Landscape Reclamation on Mangrove Forest and Coastal Areas in the Niger Delta…

<sup>20</sup>─30 years to develop into a mature mangrove forest. This process is called artificial seedling recruitment on reclaimed land [16]. In a natural seedling recruitment, after a disturbance event the first set of species that settle and colonize an area are the pioneer species. They gradually occupy the area through seedling recruitment process. In a classical case of land recuperation after landscape reclamation at Eagle Island in the Niger Delta, recruitment occurred through natural process within a space of 1–3 years. In 2014, an area measuring 100 m 50 m was dredged and sand filled. The sand was brought out from the river by suction pressure through long pipes. The sand filled area became the dumping ground for sand, where trucks evacuated the sand to buyers. The side of the sand filled area was piled up to form balkanization against the inflow of river water. The sand mining activity was abandoned after 2 years of operation. In the course of this period a small outlet was created by the side of the sand filled area, which allowed the entry of river water into the sand filled area during high tide. Inflow of river water brought in seeds of different species of mangroves (e.g. red, white and black mangroves) and seeds of nipa palm and Heritiera littoralis. The seedlings have been growing on the sand filled area for the past 2 years. The plants growing on the sand fill area are between 0.5 m and 1.0 m tall. A field observation made indicates that seeds at the end of the sand filled area had better growth than seeds at the mouth of the entrance of the balkanized sand. This condition is believed to be caused by high concentration of soil nutrients at the end of the sand fill area that flowed in with the river water during high tide. Growth may also be facilitated by the absorption of soil nutrients embedded in the first layer of soil brought in by tides. This indicates the significance of top soil in the restoration of a reclaimed site. This is a natural ecological restoration. It is a regular progress or change by

exportation of mangrove soil and mangrove propagules and allowed for

plant and animal due to natural or anthropogenic disturbances. It is the

replacement of populations in a habitat through a regular progression over time to a stable state following a disturbance. In a preliminary study conducted in the sand dredged area, soil samples were collected for physico-chemical analysis at three sites (T1, T2 and T3) from the back of the sand filled area to the entrance of the sand fill area (Figure 8). Furthermore, census of species found in the area was made at the three study sites. The results of the physicochemical analysis and the species abundance test were derived as shown in Figure 9. The result indicates that Potassium and magnesium had the highest concentration. Although they were not significantly different from each site (F2, 12 = 0.19, P = 0.83). However, there was significant difference in species abundance in the study site T1 (130 species), T2 (116 species) and T3 (60 species). The most dominant species found was white mangroves (Laguncularia racemosa) (108) followed by red mangroves (Rhizophora racemosa) (104), black mangroves (Avicennia germinans) (77) and nipa palm (Nypa fruticans) (17). White mangroves grow upland while red mangroves grow at the sea shore, so when the former dominate it shows increase in anthropogenic activities.

The next kind of management is human management [19]. It involves human beings because they are the ones that cause problems for biodiversity. It is a system where plants and animals have advantage in reserved area. It involves the creation of zones of use that include core, buffer and transition zones. The aim is to prevent the destruction of the ecosystem by human activities such as sand mining, explora-

tion, hunting and fishing.

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Figure 7.

Conversion of coastal environment to terrestrial area through deforestation and solidification to terrestrial environment in the Niger Delta, Nigeria.


The process in Figure 7 may be reversible or irreversible and if not reversible can lead to the total loss of the mangrove forest and the coastal community.
