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Impact of Invasive Nypa Palm (Nypa Fruticans) on Mangroves in Coastal Areas of the Niger Delta Region, Nigeria: Coasts in Crisis

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Invasive nypa palms (Nypa fruticans) are a major threat to mangroves and coastal systems in the Niger Delta region in Nigeria, apart from oil and gas exploration. The palms were first introduced as foreign species to curb coastal erosion over a century ago (i.e. 1906). They later became invasive and started multiplying in the last 30 years. The palms have acclimatized to the coastal environment by developing superior root system, which they use to tap available nutrients. They also have tough and buoyant seeds, which aid in their wide dispersal. These qualities of the palms had made them to have an edge over the mangroves. Oil and gas exploration, which is responsible for numerous oil spillages, is a major cause of mangrove decimation. The establishment of open waste disposal sites in coastal areas have also contributed to the changes in soil and water qualities, leading to further decline in mangroves, with a resultant increase in invasive nypa palms. The palms change the pedology, hydrology and landscape architecture of the coastal environment once they are established. Therefore, a threat to the mangroves is a threat to the entire coastal system, which benefits from the ecosystem services provided by the mangroves. Mangroves may disappear completely from the Niger Delta in the next 50 years if the encroachment of the palms continue unabated. However, this problem can be resolved by the removal of the palms through mechanical, physical or chemical means. Soils on which the palms grow can be excavated to remove the allelopathic properties, after which the palm soil should be replaced with mangrove soil. To ensure smooth re-colonization of the coast, mangroves propagules with good genetic quality should be selected, nurtured and transplanted from the nursery to the coastal areas. The mangrove propagules should be monitored and protected from further invasion by nypa palm after planting.
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Chapter 13
Impact of Invasive Nypa Palm (Nypa
Fruticans) on Mangroves in Coastal Areas
of the Niger Delta Region, Nigeria
Aroloye O. Numbere
Abstract Invasive nypa palms (Nypa fruticans) are a major threat to mangroves and
coastal systems in the Niger Delta region in Nigeria, apart from oil and gas
exploration. The palms were rst introduced as foreign species to curb coastal
erosion over a century ago (i.e. 1906). They later became invasive and started
multiplying in the last 30 years. The palms have acclimatized to the coastal envi-
ronment by developing superior root system, which they use to tap available
nutrients. They also have tough and buoyant seeds, which aid in their wide dispersal.
These qualities of the palms had made them to have an edge over the mangroves. Oil
and gas exploration, which is responsible for numerous oil spillages, is a major cause
of mangrove decimation. The establishment of open waste disposal sites in coastal
areas have also contributed to the changes in soil and water qualities, leading to
further decline in mangroves, with a resultant increase in invasive nypa palms. The
palms change the pedology, hydrology and landscape architecture of the coastal
environment once they are established. Therefore, a threat to the mangroves is a
threat to the entire coastal system, which benets from the ecosystem services
provided by the mangroves. Mangroves may disappear completely from the Niger
Delta in the next 50 years if the encroachment of the palms continue unabated.
However, this problem can be resolved by the removal of the palms through mechan-
ical, physical or chemical means. Soils on which the palms grow can be excavated to
remove the allelopathic properties, after which the palm soil should be replaced with
mangrove soil. To ensure smooth re-colonization of the coast, mangroves propa-
gules with good genetic quality should be selected, nurtured and transplanted from
the nursery to the coastal areas. The mangrove propagules should be monitored and
protected from further invasion by nypa palm after planting.
Keywords Niger Delta · Nypa palm · Invasive species · Hydrocarbon pollution ·
Mangrove · Exploration · Seismic activities · Oil spillages · Restoration
A. O. Numbere (*)
Department of Animal and Environmental Biology, University of Port Harcourt, Choba, Nigeria
©Springer International Publishing AG, part of Springer Nature 2019
C. Makowski, C. W. Finkl (eds.), Impacts of Invasive Species on Coastal
Environments, Coastal Research Library 29,
https://doi.org/10.1007/978-3-319-91382-7_13
425
cfinkl@cerf-jcr.com
13.1 Introduction
Invasive species are plants and animals that are intentionally (aquaculture, agricul-
ture, recreation and ornamental purposes) or unintentionally (humans, airplanes,
cars, shirts, ships etc.) introduced into foreign lands (Davis 2009), and become
physically and genetically more superior than their host species when they arrive.
In addition, invasive species hitch hike to foreign lands on vehicles or vessels
(Crosby 1986; Hodkinson and Thompson 1997). Similarly, species are also intro-
duced to foreign land through international trades and travels by humans who carry
crops to Africa, Asia, Europe, Australia and America. The foreign species compete
with the host species for resource and space, which leads to serious impacts on host
species ability to survive. The impact can be direct through predation, competition,
parasitism and disease, or indirect through resource competition, trophic cascade,
habitat modication (Wootten 1994), ecosystem impact through habitat structure,
disturbance regime, nutrient cycling and hybridization. Some of the invasive species
are ecosystem engineers, because they change the fundamental aspect of the physical
and chemical environment in their new location (Jones et al. 1997). Invasive species
also exhibit propagule pressure by producing large pool of source population, which
overwhelm the native species. Other impacts of invasive species in coastal areas
include: population and community impacts, morphological impacts and genetic and
evolutionary impacts. Many studies had come up with some theories concerning the
actions of invasive species. Two of these theories are biotic resistance hypothesis
and energy release hypothesis. Biotic resistance hypothesis postulates that commu-
nity diversity affects invasion success (Elton 1958). This means species rich com-
munities are more resistant to invasion. Thus if species are packed into a community
they effectively utilize the resources, and prevent the creation of empty niches,
which discourage invasive species (Elton 1958). This is because an empty niche
will lead to competition for unused and abundant resources. Likewise, consumption
by natives reduces invasion success. This is because invading species meet their
waterloo in foreign lands when native species ght back. Energy release hypothesis,
on the other hand, postulates that invasive species spread rapidly due to the absence
of co-evolved natural enemies in the introduced range (Elton 1958; Keane and
Crawley 2002). It also means that when there is an abundance of enemies in a native
range, they prevent the native species from succeeding whereas the invasive species
prospers because by leaving their home base they leave behind most of their natural
enemies. However, studies had shown that most introductions fail, for example,
starlings, a small to medium sized passerine birds in the family of Sturnidae, failed at
its initial introduction.
Nevertheless, nypa palm (Nypa fruticans) is one of those species that didnt fail,
but rather became very successful at its initial introduction. It is now a major
invasive species and a threat to coastal areas in the Niger Delta. This is because
the palms have suppressed the growth of mangroves and other coastal species with
their explosive population growth. They are able to over crowd the coastal areas
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because of the high production and effective distribution of their seeds around major
creeks and rivers in the region. They grow outwardly from the center of the forest
towards the river, constricting the waterways. The palms prevent the growth of other
coastal species by occupying every unoccupied inch of land along the coast.
However, mangrove growth is different from nypa palm growth because mangrove
supports food chains, and food webs and helps in the proliferation of other species in
the coastal environment (e.g. epiphytes). For instance, mangrove forests serve as
spawning ground for various aquatic organisms, whereas the palms destabilize
ecosystem function by pushing away many organisms (e.g. shes), and making it
difcult for local shermen to have good catch whenever they go for shing. This
results to them sailing further into the Atlantic Ocean to get more catches.
The nypa palms (Nypa fruticans) in the Niger Delta region originated from Asia
(Jones 1995), but were intentionally introduced into the Niger Delta to ght coastal
erosion in 1906 (Keay et al. 1964). The rst point of contact of the palms was
Calabar, a town in the Niger Delta, from where they spread further south to other
coastal towns along the Atlantic Ocean, aided by human activities and tidal currents.
One major cause of their spread in the coastal areas is oil and gas exploration
activities, which involved forest clearing to create room for seismic work, and
deforestation, which changed the landscape of mangrove forest from undisturbed
to disturbed state, after the entry of the exploration parties (Fig. 13.1). These actions
lead to the proliferation of several alien species such as grasses. Similarly, the arrival
of exploration teams led to the construction of boot camps and residential quarters to
accommodate eld workers, which further attracted a lot of human presence around
the forest leading to gradual urbanization of the coastal areas. The creeks and rivers
around Okrika, a host town to a major renery in the Niger Delta, have a lot of oil
facilities (e.g. pipelines, well heads, oil jetties etc), which helped to change the
conguration of the forest by making it possible for the nypa palms to invade and
colonize most areas around the coast (Fig. 13.2). In contrast, Buguma another town
has no major oil infrastructure, but few well heads with sub-surface pipelines with
limited nypa palm presence (Fig. 13.2). Nothwithstanding, during one of our eld
trips a nypa palm seedling, about 1 m tall was found growing within the mangrove
forest by the sea shore, which most likely was brought in by tidal current. The
seedling was uprooted and destroyed, but whether that singular action will prevent
further entry and growth of the palms still remains to be seen.
The palms had adapted to the environment and had become a major threat to the
native mangroves. The palms are found along the rivers of most of the coastal towns
in the Niger Delta region such as New Calabar, Nun, Imo, Saint Barbara, Saint
Bartholomew, Orashi, Bonny, Opobo, and Andoni Rivers. They occur in mixed or
pure species stands (Wang et al. 2016) at the fringes of the sea where they block
water channels and navigational routes. They also clog up drainages, thereby causing
the stagnation of fast moving streams. The palms do not only affect coastal envi-
ronments, they also affect transportation along the river by causing boat accidents,
which results in injuries and deaths (Fig. 13.3) because of poor visibility, caused by
the blocking of view of boat drivers when they meander through the creeks.
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Fig. 13.1 Mangrove forest loss in the Niger River Delta, Nigeria is as a result of urban expansion
and other anthropogenic activities (e.g. oil and gas exploration, deforestation, invasive species etc).
Mangrove loss is also triggered by agricultural activities leading to the formation of sand bars
(Kuenzer et al. 2014), and the reduction of wet mud (Wang et al. 2016)
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Fig. 13.2 Two study areas in the Niger Delta that had already been invaded by nypa palms (Nypa
fruticans). The rivers and creeks around Okrika had been over run by the palms, due to years of oil
and gas exploration activities which caused crude oil spillages while nypa palm invasion in Buguma
had been low because of low oiling activities
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13.2 Factors Inuencing Nypa Palm Expansion in the Niger
Delta Region
13.2.1 Anthropogenic Factors
Anthropogenic activities contribute greatly to the invasion and spread of nypa palms
in the Niger Delta. Oil and gas exploration and exploitation activities which began in
1956 through the striking of the rst oil well in Oloibiri town, Niger Delta was
particularly a major factor that opened up the mangrove forest to invasion by palms
(Figs. 13.4 and 13.5). Exploration for crude oil is one of the rst activities that led to
the deforestation of vast amount of virgin mangrove forest, aimed at creating a right
of way (ROW) passage for seismic lines, laying of pipelines and setting up of base
camps (Fig. 13.5). The paths created within the forest do not grow several years after
their establishment (Ohimain et al. 2008), but become passages for humans and
animals, which use the route created to penetrate deeper into the forest to plunder its
resources. Local people take advantage of the cleared area to hunt for animals and
set up crop farms while oil workers go into the forest with heavy machinery
Fig. 13.3 Nypa palms invade a small mangrove forests and also constricts a navigational route for
sea travelers at Eagle Island, Niger Delta Nigeria. Some sections of the forest had already been
dredged on the left side of the picture for the purpose of sand mining and the establishment of an
industrial complex
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that disgures the swamp and introduce foreign species that are picked up along the
way.
Hydrocarbon pollution is an outcome of exploration activities, and it occurs
during the drilling of oil wells and the transportation of crude oil through pipelines
along sea and land routes. Oil spillages occur during pre-exploration, exploration
and post exploration stages. The spilled oil changes soil and water qualities and
affects the growth of coastal organisms. Reduction in soil quality impedes the
growth of native plants, and accelerates the growth of foreign species. Studies had
shown that nypa palm seedlings grow better than mangrove seedlings when both are
planted in mangrove soil. Similarly, nypa palm seedlings survive longer than
mangrove seedlings when both are planted in polluted mangrove soil (Numbere
and Camilo 2016a). Contamination of the water body also leads to the death of
aquatic organisms and the destruction of the food chain, which depends on the
coastal life for survival.
Fig. 13.4 Google image of a major crude oil pipeline linking the Port Harcourt renery and the sea
jetty at Okrika, where crude oil is evacuated and transported abroad. Some years ago (i.e. in the year
2010) this location was exclusively a mangrove forest, but of recent most of the mangrove stands
had been taken over by the palms. This is because of constant hydrocarbon pollution from broken
pipes, and deforestation aimed at clearing the path along pipeline routes, which results in the death
of mangrove trees. (Credit: Google Earth)
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Fig. 13.5 Dredging activity to create pipeline route through the mangrove forest in Bakana town,
Niger Delta, Nigeria. (Credit: A.O. Numbere)
Fig. 13.6 Encroachment of nypa palms into mangrove forest (Rhizophora mangle) along a
waterway leading to Bakana Town, Niger Delta, Nigeria. Invasion of the palms is facilitated by
anthropogenic activities such as oil and gas exploration, dredging, sand mining, and urbanization.
(Credit: A.O. Numbere)
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Dredging activities destroys the native mangrove stands and creates an opening
for nypa palm seeds to enter and multiply. In the same vein, the contamination of the
soil as a result of oil and gas exploration activities also changes the soil quality
leading to the death of the mangroves and the proliferation of the palms as recorded
in many sites across the Niger Delta (Fig. 13.6).
Urbanization is a key anthropogenic factor that drives the growth of invasive palms.
The palms have more afnity for disturbed than undisturbed soil. Urbanization in this
context is the replacment of mangrove forest with urban centres, which promotes the
spread of palms by changing the soil quality (Fig. 13.7). This involves the destruction of
mangrove forest stands and the building of houses right in the mangrove swamp. This
action creates the way for the invasion of other alien species. Conversion of wetlands
into place of human habitation leads to the generation of human waste, which further
reduces the quality of the environment. A disturbed forest is a fertile ground for the
proliferation of the palms. The practice of aquaculture in wetland also degrade native
mangrove, and encourage the introduction of foreign species. Mangrove forest had been
degraded from high density to low density mangrove for the last 20 years in the Niger
Delta (Wang et al. 2016; Kuenzer et al. 2014).
Fig. 13.7 Building of houses right in the mangrove swamp destroys the native mangrove species
and open the way for the invasion of the coastal area by alien species such as nypa palms and a
variety of grass species. This location was formerly exclusively occupied by mangrove species, but
now only a little patch of mangrove stand still remains at the background of the picture. One of the
contributing factors is the use of the location as a refuse dump site, which changes the soil to dirty
brown that is mixed with greenish algae (e.g. spirogyra). (Credit: A.O. Numbere)
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13.2.2 Pedology/Changes in Soil Condition
Mangroves are habitat specialist, and grow only in coastal areas (Nagelkerken et al.
2008). Therefore, a change in soil condition from swampy to sandy soil is
detrimental to their survival. Mangroves grow better when they are in their native
soil, which is swampier and richer in nutrients than the nypa palm soil. This is in
agreement with a previous study which indicates that soil effect had more inuence
on invasion success than species richness (Stohlgren et al. 1999). The typical
mangrove soil is coffee brown in color, slightly muddy and has a pungent
ammonia-like smell, which breathes life into the mangrove forest and accelerates
the growth of organisms. On the other hand, the palms grow on a variety of soils
such as mangrove soil, muddy soil, sandy soil and algae-infested soils. Studies done
using soils from different locations show that growth in height of nypa palm
seedlings was mainly inuenced by soils derived from highly polluted forest than
soils derived from lowly polluted forest. Another study also indicates that nypa
palms grow better than mangroves in mixed forests (i.e. a combination of
mangrove and nypa palm trees growing together) than in pure forest (Wang
et al. 2016). This is one of the reasons why the palms out-compete the mangroves
when they inltrate mangrove forest (CEDA 1997). Nypa palm has better growth
in mangrove soil than in its own soil. Studies had shown that the growth of nypa
palm seedlings in mangroves soils is as a result of the utilization by the palms of
the un-used nutrients that are locked within the mangrove soil. One of the
conclusions of this study is that nypa palm performed better in mangrove soil
and worse in its own soil, in terms of growth in height and production of leaves.
Similarly, nypa palm produced more seeds than mangroves in mixed forest. This
gives the palms advantage over mangroves because with time the seeds of the
palms will germinate and colonize the entire area. This situation is a recurring
factor in many locations in the Niger Delta.
During several eld trips to many locations it was observed that mangroves
growing in core nypa palm forest dont have better growth. This led to the conduc-
tion of a pilot study to test the growth performance of mangrove and nypa palm seeds
in mangrove and nypa palm soils. We collected soils from both mangrove and nypa
palm forest and placed them in a swamp box (Numbere and Camilo 2017b). Twenty
ve (25) seeds of mangroves (R. racemosa) without blemish were planted in each
soil, and left under semi-natural conditions for seven months (i.e. MarchOctober).
The plants were watered daily with river water collected in-situ, and left in the
open, under the elements of the weather. The result was stunning, and provided
some answers to why the palms are always performing better than the mangroves,
and why the palms had continuously colonized several mangroves forest in the Niger
Delta in the last few years. The result showed a robust growth of mangrove seeds
planted in mangrove soil and a stunted growth of mangrove seeds planted in nypa
palm soil (Fig. 13.8). This experimental growth in a nursery is what has been
replicated in the natural environment, which had made the palms a more superior
competitor than the mangroves, leading to the domination and eventual elimination
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of mangroves in several locations. More studies are ongoing with more replications
to reinforce the hypothesis that invasion of nypa palms in mangrove forest has a lot
to do with changes in soil quality.
13.2.3 Hydrology
Dredging and sand lling activities change the hydrology and affect mangroves and
other coastal species (Fig. 13.9) (Ohimain 2004). Sand lling brings in excess
sediments along with foreign species into wet land region, which smothers and
overwhelm native species. Sandy soil that is pumped from the bottom of the sea unto
the shore comes along with foreign species, which invade the coastal areas. Some
aquatic organisms such as mangroves do not grow on sandy soil. Moreover, the
change in creek size inuences tidal ow rate, and affects stream physico-chemistry.
Similarly, expansion of the coast through channel canalization (Fig. 13.10) leads to
the inadvertent entry of invasive species while reduction in stream size increases
tidal pressure with ripple effect on stream chemistry (e.g. salinity) and species
population dynamics (e.g. increased competition). Changes in the salinity level of
the stream through dredging activities affect species composition and distribution.
Fig. 13.8 Swamp box experiment showing two partitions of: (a), mangrove soil and (b) nypa palm
soil. Twenty ve mangrove seeds were planted in each section. They were watered daily with river
water, and monitored for seven months, MarchOctober, 2017. The result indicates that mangrove
seeds in mangrove soil had robust growth while mangrove seeds in Nypa palm soil had retarded
growth. Result of this study is a classical example of what happens in the natural environment where
Nypa palms are quickly colonizing the coastal areas at the detriment of the native mangrove species.
(Credit: A.O. Numbere)
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Mangroves are generally halophytic, but the distribution of individual species
depends on the salinity level of the location. For instance, Rhizophora species are
less halophylic whereas Avicennia germinans are more halophylic (Lugo 1980),
which affects their distribution. During the transition period after dredging, the area
is usually invaded by opportunistic foreign species as the native species migrate to a
more habitable environment.
Dredging of the coastal areas to lay pipelines disturb the soil structure and
composition and destabilize the growth of mangroves and other coastal species.
Nypa palms invade areas made bare by deforestation. The dredging activity changes
the soil and water quality and prevents the mangroves from growing, leading to their
gradual death and loss from the environment (Fig. 13.10). In the same vein,
urbanization and improper waste disposal are leading to the disappearance of
many mangrove forest along the coastal areas (Fig. 13.11).
Channel reduction changes stream chemistry and size, and lead to the formation
of mangrove islands, which are a preparatory stage for the complete elimination of
Fig. 13.9 Google Earth image of Buguma, a town in the Niger Delta, Nigeria that was sand lled in
1984 for the purpose of building houses to accommodate increasing population of the local
residents. Till date the sand lled area (white patch) has not supported the growth of any mangrove
forest, rather different foreign species such grasses had dominated the area covered by the sandy
soil. Similarly, some tributaries connected to the river had been blocked by the sand. Some seeds of
nypa palms were recently detected on the shores of the river, which indicates that in a matter of
some years the remnants of the mangrove forest seen in the picture would be endangered and
may go into extinction in the next 20 years if nothing is done. (Credit: Google Earth)
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small mangrove communities (Fig. 13.12). Stream reduction also constricts space
for the free movement of species, and triggers competition amongst aquatic organ-
isms. For instance, some parts of Eagle Island in the Niger Delta, previously had a
combination of red (R. racemosa) and white (A. germinans) mangroves, but now
have only white mangroves because of changes in hydro-chemistry as a result of
sand dredging and sand lling that took place in the area (Fig. 13.12a). It was
observed that the white mangroves performed better in sandy and disturbed soils
than the red mangroves. Red mangroves (Rhizophora) are the most dominant coastal
species in core undisturbed mangrove soils. Therefore, during dredging and con-
tamination of the coast they become the rst victims of long term soil degradation.
The second location is Eagle Island (Fig. 13.12b), which has most of its mangrove
stands destroyed. This is because of the toxic effect of sawdust that was dumped into
the river by a wood mill industry located nearby. But this physico-chemical change
does not affect the palms, which continued to grow as shown in the background in
Fig. 13.12b. The palms generally thrive in polluted soil, thus they are not affected by
the organic waste materials that are dumped into the river.
Fig. 13.10 Mangrove swamp dredged to lay pipelines that connect an oil tank at the far end of the
picture. Years of disturbance of this coastal location at Eagle Island, Niger Delta, Nigeria through
sand mining, dredging and improper waste disposal had exposed the mangrove forest to invasion by
nypa palms and other alien species as seen on the left side of the picture. (Credit: A.O. Numbere)
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13.2.4 Root Micro Structure
Nutrient absorption is carried out by the roots, and determines the rate at which the
plant adapt to their environment. Microscopic study of the roots of red mangrove and
nypa palm using electron microscope in the laboratory of the Department of Animal
and Environmental Biology, University of Port Harcourt, Nigeria, indicates that the
roots of palms are structured to carry out better nutrient absorption than roots of
mangroves. The root of the palm is light in texture, hollow and straw-like while the
root of red mangrove is thick and tightly packed (Fig. 13.13). The root of nypa palm
is completely embedded in the soil and grows deep down the soil prole while
mangrove roots are mostly adventitious with many parts growing outside the soil in
other to carry out aerobic respiration. The palm roots go deep down the soil prole to
tap unused nutrients while some roots of mangroves grow at the surface layer. In
addition, mangrove roots are woody and less permeable as compared to the roots of
nypa palm that are tender and highly permeable.
Fig. 13.11 A patch of mangrove stand (Rhizophora mangle) is boxed into a corner between
some urban settlements and invasive species. Already the mangrove stand on the left hand side had
withered. Between both stands is a heap of refuse dumped by inhabitants of the adjoining
apartments, which had changed the color of the river to green due to algal infestation. The
proliferation of urban settlements around the coast had led to an increase in waste generation,
which had contributed to the invasion of alien species. (Credit: A.O. Numbere)
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Again, in another study mangrove roots were found to have more un-transported
nutrient content as compared to nypa palm roots when 20 mangrove and 20 nypa
palm root samples were dissected and analyzed for nutrient content in the laboratory.
The result indicate that average total nutrient content was more in mangrove roots
Fig. 13.12 Changes in coastal hydrology impact (a) white mangroves (Avicennia germinans)
through channel reduction via sand lling and (b) red mangroves (Rhizophora racemosa) through
changes in river physico-chemistry as a result of pollution. Both factors affect the distribution of
mangroves leading to the formation of mangrove islandsand the intrusion of nypa palms as seen
in the background in (b). Figure 13.12 (a) has white mangroves (Avicennia germinans) and no red
mangroves around because of changes in salinity, while in Fig. 13.12 (b) the red mangroves
(Rhizophora racemosa) are gradually being replaced by nypa palms. Similarly, (b) shows one of
the few last stands of red mangrove (R. racemosa) trees being surrounded by nypa palm in this
location in Eagle Island, Niger Delta, Nigeria. (Credit: A.O. Numbere)
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(123.9 121.1 mg/kg) than in nypa palm roots (44.9 40.7 mg/kg). The nutrient
content is a combination of Nitrogen, Phosphorous, Potassium and Nitrate. Further-
more, the result of this study indicates that there was no signicant difference
(P¼0.55) in nutrient content between nypa palm and mangrove root. Nonethe-
less, the low amount of nutrient content in the roots of nypa palm could mean that
there is a faster transmission of nutrients from the root to other parts of the plant as
compared to the mangrove root. However, out of all the nutrient elements analyzed
potassium (K) was the most dominant, and had higher concentration in mangrove
root than in nypa palm root.
Fig. 13.13 Root structure of (a) nypa palm and (b) mangrove. Nypa palm roots are light and fully
embedded in soil while mangrove roots are thick and adventitious. (Credit: A.O. Numbere)
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13.2.5 Seed Buoyancy
The exocarp of nypa palm seed acts like a oater (Fig. 13.14), and enables the seeds to
remain aoat for long in the aquatic environment. The buoyancy of the seed makes it to
travel thousands of kilometers in and around the coastal regions of the Niger Delta. As a
result of this situation, one would hardly nd a location around the riverine areas of the
Niger Delta without the presence of nypa palm seeds. Another advantage of the seed
structure is that it has tough outer covering, which prevents it from being soaked by
water or permeated by pollutants such as crude oil. The toughness of the seed also
prevents it from being consumed by crabs or other organisms around the mangrove
forest, unlike the mangrove propagule that is soft, palatable and edible.
13.2.6 Landscape Changes
Human activities lead to the changes in landscape architecture in coastal areas,
which facilitate the invasion of foreign species (Wang et al. 2016). The use of the
coastal area as a waste disposal site had led to the complete displacement of
Fig. 13.14 Nypa palm seeds occur in groups of 2030 seeds and are tough and have high buoyancy
rate, which enables them to oat to far distances around coastal areas of the Niger Delta, Nigeria
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mangroves in some locations such as the Eastern Bye Pass section of a prominent
Creek in the Niger Delta called the Ntawogba creek(Fig. 13.15a). This location
was formerly an exclusive mangrove forest. Many other places that were once
occupied by mangroves are now completely invaded by the palms in mixed or
pure forest stands. As mangroves disappear, the ecosystem services they render
also disappear along with them such as re wood, coastal protection, ood control,
Fig. 13.15 (a) A time-line of a former mangrove forest that was completely invaded by nypa palms
in 2014; (b) The same location after it was sand lled in 2017 (i.e. Eastern-Bye Pass Creek, Niger
Delta). Anthropogenic activity such as pollution, improper waste disposal, deforestation etc.
contributed to the disappearance of the mangroves from this once vibrant mangrove forest. Since
the palms had no economic value it was bulldozed by the local authority and sand lled. It is now a
proposed site for constructing industrial and residential quarters. (Credit: A.O. Numbere)
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shoreline protection etc. (Polidoro et al. 2010). The palms grow and block drainages
(Fig. 13.15a), which are then cleared by dredging causing harm and disgurement of
the landscape. The dredging equipment used in clearing the forest further stresses the
coastal environment by destroying benthic organisms. In some cases complete sand
lling is done to reclaim the areas lost to nypa palm (Fig. 13.15). Observations had
shown that the reclaimed locations are never returned to their original form, but are
rather used as platform to construct developmental projects, such as housing com-
plexes, industries, lling stations, ofces, apartments, etc.
Invasive nypa palm obstructs waterways and affects navigational activities
(Fig. 13.16). The palms constrict the width of the river channels as they grow and
expand (Fig. 13.16), which cause maritime accidents of sea crafts. Constriction of
the river channel affects the free movement and population structure of aquatic
organisms. Canalization and sand dredging lead to sedimentation. This occurs
when stands of palms act as barriers to water ow and lter to waste materials
carried by river into coastal areas (Fig. 13.17). Accumulation of sand from other
locations, especially from dredged soils changes the coastal area to sandy soil, and
prevents the growth of mangroves and other aquatic organisms.
Fig. 13.16 A former mangrove forest, over ran by palms in Asarama community in the Niger Delta
Nigeria. The pattern of growth of the palm is to stie other plants around it and to block the water
channels thus, preventing the free ow of oxygenated water. Non-owing water around the forest
traps waste, which decomposes to degrade the water quality. This increases the effect of pollutants,
which are inimical to the health of the mangroves and the coasts in general. (Credit: A.O. Numbere)
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13.3 Transformation of Coastal Areas from an Aquatic
to a Terrestrial System
Mangroves were the dominant species along the coastal areas of the Niger Delta
prior to the 1990s, but because of anthropogenic activities of oil and gas explora-
tion, urbanization, deforestation and poor waste management, they had been
displaced by nypa palms in many locations. The pattern of growth of the palms
had made them to obstruct, and change the architecture of the stream channel leading
to loss of several coastal species. Local authorities carry out sand lling and
dredging of nypa palm invaded areas in other to reclaim the lost mangrove forest
as shown in Fig. 13.18a, b. Similarly, private agencies mine sand from coastal areas,
which they sell to construction companies for the purpose of building. In addition,
the sand-lled locations are set aside for building projects. This situation can be
described as a horizontal irreversible coastal change (Fig. 13.18a). This is because
the area cannot be reverted to its original form after it has been converted from an
aquatic to a terrestrial system. This process thus leads to the total elimination of all
aquatic organisms in that coastal system including pelagic and benthic organisms,
which is not good for the sustainability of the environment. This is because the coast
helps to stabilize the environment by removing atmospheric carbon dioxide, and
reducing the impact of global warming. The coast is also a haven for biodiversity
such as aquatic and amphibious organisms. Therefore, the loss of the coast is
dangerous for the whole environment. However, in this circumstance the best
management strategy to adopt is a triangular reversible transformation
Fig. 13.17 Accumulation of waste materials (log, dirt, branches etc) trapped at the base of nypa
palm (Nypa fruticans) prevents the free ow of materials in the creek at Okrika, Niger Delta Nigeria.
(Credit: A.O. Numbere)
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(Fig. 13.18b). This can be done after the area had been successfully colonized by the
nypa palms in mixed or pure forest. To restore the site, the palms should be removed,
and in their place mangrove seedlings planted. This can be done when the area is
passing through its cycle of change from mangrove to mixed forest or from mixed
forest to pure nypa palm forest. Physical, mechanical and chemical means can be
used to eliminate the palms. Mangrove soil should then be brought in, and spread all
over the area, after which young mangrove seeds are planted to ensure a rejuvenated
growth of the mangroves.
13.4 Conditions That Favor Nypa Palm Invasion
of Mangrove Forest in the Niger Delta
The entry of nypa palm into the Niger Delta was made possible by an invasion
pathway (Carlton and Ruiz 2005) established by the presence of the Atlantic Ocean
(Richardson et al. 2000), which facilitated travel from Asia to Nigeria, and made the
intentional transfer of the seeds successful (Keay et al. 1964). On arrival to the new
habitat the palms got adapted and became physiologically tolerant to the new
environment. The life history of the palms matched the new environment. The
palms also benetted from untapped resources in the mangrove forest. These
untapped resources are empty niches created by massive deforestation for oil and
gas exploration and urbanization. These conditions thus created a disturbed envi-
ronment, which encouraged a successful invasion, colonization and expansion.
Incessant mangrove tree cuttings for re wood also reduced the native mangrove
Fig. 13.18 Transformation of mangrove forest to (a) sand ll and (b) pure mangrove forest.
Conversion of mangrove forest to sand ll area is a total loss to the coast. This pattern of change
(Fig. 13.18) is often observed in the Niger Delta region whenever nypa palm forest is removed from
a location. There is often no restorative effort aimed at bringing back the original mangrove forest,
rather the area is reclaimed for other developmental projects or urbanization activities. But the best
restorative effort is to bring back the area to its original state (Fig. 13.18b). This is to ensure that the
mangrove forest does not slip into extinction in some years to come. (Credit: A.O. Numbere)
13 Impact of Invasive Nypa Palm (Nypa Fruticans) on Mangroves in... 445
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species diversity, and led to a geographical isolation that are characteristics of an
invaded community. This is the reason why the palms are having better growth in
mangrove soil than in nypa palm soil. Field observations also show that the palms
produced a lot of seeds as they become adapted to the new environment. In a seed
enumeration study in a mixed forest, it was observed that the ratio of the palm seeds
to mangrove seeds in a 20 m x 20 m plot was 27:1. This show that the palm seeds in
most locations visited out-numbered the mangrove seeds (Fig. 13.19). If this trend
continues it wont take too long for the palms to completely overwhelm and colonize
the entire region (Wang et al. 2016).
Additionally, continuous anthropogenic disturbance is a major cause of the
spread of nypa palms to several other locations after the initial introduction (Kowarik
2003). One of such actions of humans is improper waste disposal within the
mangrove forest. This condition makes the environment to be conducive for the
palms to grow and proliferate around the coast at the detriment of the mangroves
(Fig. 13.20).
Another consequence of urbanization, apart from the physical deforestation of the
forest, is the bringing of people closer to the coast so that they will appreciate nature
Fig. 13.19 A classic example of propagule pressure of nypa palm seeds in a mangrove forest. The
palms are waiting to invade and displace the mangroves in a sand lled location in Asarama town,
Niger Delta, Nigeria. On the left side of the picture are seeds of the white mangroves
(A. germinans) hanging on a tree. It is not known if the mangrove seeds can withstand the difcult
sandy environment to grow and populate the area, since the muddy mangrove soil on which they
thrive is no longer available. (Credit: A.O. Numbere)
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Fig. 13.20 Waste dump sites in (a) nypa palm forest and (b) mangrove forest in the Niger Delta,
Nigeria. This is one of the consequences of urbanization when people live too close to the coast. The
palms grew bigger while the mangroves die gradually with the introduction of waste to the coastal
areas. Both areas were exclusively mangrove forest 30 years ago, but continuous dumping of waste
converted these areas into a nypa palm (Nypa fruticans) forest. (Credit: A.O. Numbere)
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better, which is not a bad idea. But the problem is that when people live so close to
the coast, and dont have good waste management habit, there is a tendency for them
to convert the river to a waste dump site. The coast becomes a victim of increased
waste load. In some locations the coast serve as sites for constructing pier latrines
especially in the hinter lands where people dont feel the presence of government, in
terms of provision of social amenities. The wastes generated when dumped in the
river are distributed by tidal currents to other locations. Organic waste when dumped
into the river changes the stream chemistry, which leads to eutrophication and
increase in growth of foreign species such as water hyacinth, water lilly, macro-
phytes etc. In Buguma over nine different coastal and non-coastal plant species were
found within the mangrove forest. This invasion is as a result of the dredging activity
that took place several years ago, which converted the swampy soil to sandy soil
(Fig. 13.21).
Fig. 13.21 Different kinds of mangrove and non-mangrove species found in sand lled mangrove
forest in Buguma, Niger Delta, Nigeria. (a) Nypa palm (Nypa fruticans), (b) Black mangroves
(Laguncularia racemosa), (c) Conocarpus erectus (d) Mangrove associate, (e) Red mangrove
(Rhizophora racemosa)(f) Mangrove fern, (g) White mangrove (Avicennia germinans), (h)
Heriteria littoralis (i)Acrostichum aureum spp. (Credit: A.O. Numbere)
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13.4.1 Interaction Effect
The combined action of urbanization, improper waste management and pollution
(Fig. 13.22) contributes to the proliferation of invasive nypa palms and other
alien species in the Niger Delta, Nigeria. These actions are detrimental to the
Fig. 13.22 The interaction effect of (a) urbanization and (b) hydrocarbon pollution contribute to
the proliferation of nypa palms and other alien species in coastal regions of the Niger Delta, Nigeria.
Figure 13.22 (a) shows houses built after the mangrove forest was cut, dredged and used as site for
building residential quarters, Still at the foregound of the picture the remaining mangrove stands had
already been invaded by palms and other aliens species while in Fig. 13.22 (b) the dark
and scorched area is caused by re from spilled crude oil and on the left of the picture is a nypa
palm stand that had already gained a foot hold in the mangrove forest
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coastal system because they reduce the aesthetic value and make them vulnerable
to total destruction through dredging.
13.4.2 Impact of Invasive Nypa Palms on Coastal Ecology
of the Niger Delta
The branchless nature of nypa palms excludes a host of coastal organisms that would
have benetted from their presence. For instance, birds cant perch on and build their
nest on the palms, which excludes that aspect of the food chain. Similarly, termitar-
ium of termites and nest of ants cannot be found on the palms, since they have no
branches and no stem on which to build. Their deep underground roots host little or
no shell organisms such as corals, barnacles and mullets. Nypa palms also have low
litter fall yearly (Numbere and Camilo 2016), which exclude decomposition activity
as experienced in mangrove forest (Numbere and Camilo 2016). In the case where
there are a drops of leaves due to wind action, the leaves decompose slowly because
of their brous nature as compared to mangrove leave litter that is leathery and
succulent. One important coastal resource derived from mangroves, apart from sh,
is rewood. The palms cant provide it because they lack the stems. The growth of
the palms without stem also affects the free movement and distribution of species
within the forest. The hard outer covering of the seed (exocarp) makes it difcult for
most organisms to feed on it as compared to the tender succulent propagules of
mangroves which are consumed by the West African red mangrove crabs
(Goniopsispelii), and other organism living along the coast.
It was observed from several eld trips in this region that the presence of palms in
the coastal environment automatically changes the soil chemistry and physical
appearance of the soil by converting it to dirty mud. This kind of soil prevents the
growth of mangroves and excludes numerous aquatic organisms that usually thrive
in mangrove forest swamps. The ability of the palms to trap and accumulate debris
within the forest also poses major environmental and ecological problems. This is
because the dirty environment makes it less conducive for the breeding and
spawning activities of many aquatic organisms especially the shes.
13.5 Management Strategies
Invasion Control This involves the physical control, which is the destruction of
unwanted plants by manual (i.e. digging and pulling) or mechanical (i.e. swamp
buggies) methods (Figs. 13.23 and 13.24) or chemical control, which is the use of
chemicals such as pesticides and herbicides to destroy alien plants. Biological
control involves the enhancement of the genetic quality of native mangrove species
through selective production in nurseries to promote robust growth. In addition, the
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Fig. 13.24 This location is the same as Fig. 13.23. It shows a nypa palm resurgence 2 years after
the destruction of the forest by swamp buggy. This indicates that the palm stump can proliferate fast
if not completely uprooted and destroyed outside the swamp
Fig. 13.23 This area is a creek that was exclusively occupied by mangrove forest some years ago,
but have been invaded by the invasive nypa palm (Nypa fruticans), which blocked the creek. The
palms were destroyed with a swamp buggy to free up the adjoining clogged up canal. (Credit:
A.O. Numbere)
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restored forest is to be lled with core mangrove soils to prevent the negative
physicochemical (i.e. allelopathic) effect of nypa palm soil left behind.
Species Based Control This involves experimental research aimed at determining
the most effective strategy to embark on based on the particular location. For the
nypa palms, studies had shown that, they gain foothold in their new environment by
changing the soil chemistry, at the detriment of the host species. Therefore, to
eliminate this threat, it is important to remove the nypa palm soils along with the
plant completely and to re-introduce mangrove soils to facilitate rapid growth and
re-colonization of the area.
Invasion Prevention This involves the identication and regulation of the invasion
pathway. For instance dredged spoils, (i.e. waste from dredging activity) that are
dumped on fringing mangrove forest can be isolated (Ohimain 2004) and
decontaminated of foreign species through heating, chlorination and irradiation
etc., to prevent contamination of the host species by invasive nypa palm. This is
because dredged spoilaffects surface topography and hydrology of the coasts
(UNEP 2011). Transport trucks and dredging equipments apart from disguring the
coasts, also carry foreign organisms in soils lodged in their wheels and parts from
different locations. Invasion of palms is through dispersal by tidal currents; therefore
restored mangrove sites should be fenced off with wire or net gauze to prevent the
inltration of the palm seeds into the newly re-introduced mangrove restoration site.
13.6 Conclusion and Recommendations
Studies had shown that the nypa palms in the Niger Delta had fullled the conditions
necessary for a successful invasion and colonization. The war therefore, should be
taken to them through the adoption of physical, mechanical, chemical and biological
method of control. Nypa palm should be removed from all mangrove forests, creeks
and coastal areas physically or mechanically using swamp bulldozers. Then their seeds
and seedlings should be hand-picked or completely up-rooted and destroyed to prevent
resurgence. In 13 months time the area should be re-visited and the remaining hidden
seedlings that had grown out of the soil pulled out to prevent the re-growth of the
palms.Thenypapalmsoilshouldbeexcavatedandreplacedwithmangrovesoil
before the planting of mangrove seedlings. This is because studies had shown that
mangroves dont thrive well on nypa palm soils. The removal of the nypa palm soil
will remove the window of opportunity for the re-entry of the palms.
Quick action is therefore, necessary because the palms had already colonized
almost a quarter (25%) of the mangrove forest and are in the verge of completely
taking over the remaining coastal areas left in the Niger Delta (Fig. 13.25). The
palms are advancing rapidly, and if nothing is done, in the next 50 years they might
overwhelm and take over the entire coastal areas. But with the timely destruction of
the palms and the restoration of mangroves forest, this situation can be turned
around for the better.
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... Nipa palm reduces the firmness of the soil by its prostrate underground stem, thus predisposing the soil to coastal erosion that is currently being witnessed. Numbere (2019) reported factors that have made nipa palm outcompete mangroves in the Niger Delta, which include the development of a superior root system for anchorage and intensive nutrient uptake, fast and high productivity, and hard and buoyant seeds, which facilitated their widespread dispersal. They appear to strive better in a polluted or disturbed environment, including oil-, effluent-and solid waste-polluted areas, areas with modified topography, and hydrology arising from dredging and sand filling activities. ...
... Solid and liquid wastes disposal during operations can be detrimental to biodiversity. Numbere (2019) reported that spillage from oil and gas exploration is a major cause of mangrove destruction in the Niger Delta. Major drivers of forest cover loss were attributed to oil exploration, population growth and infrastructural development (Akpan-Ebe 2014). ...
... Oil exploration appears to facilitate nipa palm invasion of mangrove areas. Numbere (2018Numbere ( , 2019 listed some of the effects of oil exploration on the environment. They considered petroleum exploration as pioneering the opening up of forests, creating dredged canals and right of ways for seismic operations, access for drilling and installation of oil production infrastructure, such as wellheads, laying of pipelines and flowlines, flowstation and compressions station, and establishment of staff quarters and camps. ...
Chapter
Cultural or indigenous practices refer to long-standing traditions and ways of life of specific communities or locales. These practices are place-based and often location- and culture-specific. Plants are integral to livelihood especially in indigenous communities within the Global South. Ethnologists including ethnobotanists continue to enumerate the interface between nature and culture, which addresses the need to provide quality information for plant conservation and their sustainable utilization. Plant conservation is the wise use of plant resources by the present generation so that future generations can benefit. Traditional conservation ethics protect plant diversity and natural resources because local communities consider themselves as the major stakeholders. Globally, support for contemporary plant conservation approaches exists whereas none exists for traditional methods. Some traditional systems used for plant conservation through their utilization include taboos, totemism, rituals, domestication, reserves, secrecy, selective harvesting, sacred groves, etc. Totemism is the practice-based consciousness of the supernatural link that exists between people and specific objects including plant species, natural resources and or objects made from these items whereas taboo is the forbidden practice of using or consuming some plant species, natural resources and objects or their parts (totems). Sacred groves are described as patches of land considered sacred and conserved by indigenes through sociocultural, economic and religious observances and include traditional sacred groves, temple groves, burial and cremation grounds, etc. like the Asanting Ibiono sacred forest, Nigeria; Anweam sacred grove within the Esukawkaw forest reserve, Ghana; sacred Mijikenda kaya forest, Kenya; Kpaa Mende sacred grove, Sierra Leone; Thathe Vondo holy forest Limpopo, South Africa and Kwedivikilo sacred forest, Tanzania. These largely informal conservation and utilization practices have several ecological, sociocultural and economic relevance. They have contributed towards the protection of plant species like Lippia javanica, Milicia excelsa, Adansonia digitata, Spathodea campanulata, Ziziphus mucronata and Ficus thonningii. However, growing pressures from human population boom, reduced environmental quality, and neglect of sociocultural norms and traditional belief systems are undermining the relevance of these practices. Therefore, it is essential to document these practices, enlighten future generations of their importance and institute legal instruments to promote the sustainable management and application of these cultural heritage and natural resources for societal development.KeywordsCultural practicesEthnobotanyPlant conservationTaboos and totemsGlobal SouthSustainable development
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... This may indicate that the Niger delta is presently minimally anthropogenically impacted. Although vegetation degradation [32,60], channel dredging [45], and sand mining [64] have been reported within the Niger delta lately, our Ibe and Anita [45] have identified waves, tides, and fluvial agents as the key control of the Niger delta coastline dynamics. However, spatial process variation has long been established in the Niger delta literature, including the increasing tidal amplitude from west to east (e.g., [37,44]); more energetic waves in the western-to-central section relative to the eastern side (e.g., [37,45]); and greater fluvial discharges in the central part at the expense of the flank areas (e.g., [35,56]). ...
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... Anthropogenic activities along delta coastlines tend to promote accelerated land subsidence, alter the fluvial and coastline hydrodynamics, and compromise the coastlines' natural defence mechanisms (e.g., [18,59]). Specifically, human activities, such as extensive vegetation degradation, coastline engineering (e.g., sand replenishment, groynes, and revetments), location of oil and gas handling facilities, and the dredging of channel mouth sand bars to aid oil-related navigation, have been documented along the Niger delta coast (e.g., [45,57,60]). ...
... This may indicate that the Niger delta is presently minimally anthropogenically impacted. Although vegetation degradation [32,60], channel dredging [45], and sand mining [64] have been reported within the Niger delta lately, our Ibe and Anita [45] have identified waves, tides, and fluvial agents as the key control of the Niger delta coastline dynamics. However, spatial process variation has long been established in the Niger delta literature, including the increasing tidal amplitude from west to east (e.g., [37,44]); more energetic waves in the western-to-central section relative to the eastern side (e.g., [37,45]); and greater fluvial discharges in the central part at the expense of the flank areas (e.g., [35,56]). ...
... This may indicate that the Niger delta is presently minimally anthropogenically impacted. Although vegetation degradation [32,60], channel dredging [45], and sand mining [64] have been reported within the Niger delta lately, our study suggests that current influence of the human agency on the delta's morphodynamics process remains moderate. ...
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The purpose of this study was to analyse the shoreline movement of the Niger delta, specifically focusing on the spatial pattern of the delta’s shoreline behaviour during 1986–2019. We employed satellite data of medium spatial resolution (20–30 m) to delimit the delta shorelines representing specific time in order to determine the rates of the delta shoreline migration. Our results show that the delta shoreline has changed nearly in equal proportion between erosion (50.3%) and accretion (49.7%), at mean (maximum) rates of 3.9 m/yr. (26 m/yr.) of erosion, and 4.0 m/yr. (27 m/yr.) of accretion. Further analysis indicates that the highest shoreline migration is seaward (>200 m) though the ratio of the shoreline distance in recession (54%) exceeds that which is in accretion. Our analysis did not reveal any entrenched spatial pattern of shoreline behaviour but rather highlights a random occurrence of hotspots in both shoreline erosion and accretion over space and time. We have also showed that by applying the statistical mean-removed shoreline approach, the overall trend of a delta shoreline movement can be vividly discriminated. In conclusion, since the Niger delta shoreline dynamics is most intense at the delta river mouths, we suggest this is likely due to the interaction between waves and river discharge in these locations
... The palms use their tiny, permeable and fibrous root system to absorb soil minerals. They also produce allelechemicals, which prevent the growth of other plants around them [21]. Apart from edaphic factors which affects soil properties, anthropogenic factors also contribute to rapid changes in soil composition and soil chemistry, For instance, oil and gas exploration lead to hydrocarbon pollution [22,20] and affects soil chemistry [23] ( Alongi, 2009). ...
... Apart from edaphic factors which affects soil properties, anthropogenic factors also contribute to rapid changes in soil composition and soil chemistry, For instance, oil and gas exploration lead to hydrocarbon pollution [22,20] and affects soil chemistry [23] ( Alongi, 2009). In the same vein, deforestation of mangrove trees to pave way for exploration activity [21] impact mangrove growth [24] leading to reduction in species abundance. It is thus postulated that the rapid growth of palms in mangrove forests may signify their affinity and adaptation to coastal soil. ...
Article
Invasion of Nypa palm into mangroves is a problem in the Cameroon Estuary. Soil variability is one of the dominant features that support Nypa palm establishment. The objective was to characterize the soil under the different mangrove stands; Purely Nypa palm stands (A), mixed stands i.e Nypa palm and other mangrove species (B) and other mangrove species i.e Nypa palm free (C), determine the principal soil characteristic critical for Nypa spread. 9 plots of 20 x 20 m were laid in each of the sites. 27 soil samples were collected in the North, West, South East and Center at a depth of 30 cm in these three sites using a soil auger. The results in the three sites indicated that; soils were acidic (3.87- 4.39), pH values did not significantly differ (alpha >0.05), organic matter was low in A (12.32%) and B (16.35%).Soil Organic Carbon ranged from (4.52 to 7.06%). High percentage of organic carbon content was recorded in C (7.06%). Low percentage of organic carbon was found in A (4.52%). Total nitrogen varied from 1.04 g/kg, 1.70g/kg, 1.80 g/kg in sites C, A and B. In all the mangrove stands, the values of Exchangeable Ca content were below 4.0 cmolkg-1. Soil texture in the three sites were; sandy, clay and silt. Power test showed no significant different in soil types between the three sites (p>0.05). According to the component matrix the factor is positively loaded by soil EC, moisture content, organic matter, organic carbon, N, C/N, CEC, Ca, Mg, K, Na, Clay, Silt, and negatively loaded by the percent sand. This study therefore, suggests that since soil plays key role in Nypa palm establishment, there should be constant monitoring of soil quality to forestall drastic changes that will jeopardize the survival of the mangroves. Nypa palm seedlings should also be physically removed from mangrove forest to prevent colonization. In addition, more mangrove seeds should be planted in deforested mangrove areas to close the window of opportunity for the palms.
... This circumstance shows that the mangrove forests in this area have been most disturbed, especially due to anthropogenic activities. It has been reported that N. fruiticans is an invasive species that is able to suppress the growth of mangroves and other coastal species and has an explosive population due to high seed productivity and effective distribution of seeds whose spread is aggravated by anthropogenic activities (Numbere 2019). In addition, various studies across the world have indicated that nipah has escaped to areas outside its natural habitat, making it invasive (Duke 1991;Bacon 2001;Numbere 2018). ...
... The pile of sludge due to sedimentation increases the amount of dirty sludge because it is mixed with the waste material, thereby reducing the physical and chemical quality of the soil. This results in inhibition of mangrove growth, disrupts the spawning process of aquatic organisms, and creates ecological problems (Numbere 2019). Mangroves are known to be used as excellent fish spawning grounds and the invasion of nipah can disrupt the stability of the aquatic ecosystem. ...
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Eddy S, Basyuni M. 2020. The phenomenon of nipah (Nypa fruticans) invasion in the Air Telang Protected Forest, Banyuasin District, South Sumatra, Indonesia. Biodiversitas 21: 5114-5118. Disturbed mangrove forests such as the Air Telang Protected Forest (ATPF) do not have plant formation as natural mangrove forests and tend to be invaded by Nypa fruticans locally called nipah. The purpose of this study was to describe the phenomenon of nipah invasion in ATPF as a result of anthropogenic activities and its effects. The field survey was carried out by determining several sampling points according to the actual conditions of the area using the Geographic Information System/GPS. During field survey, data were collected in the form of descriptions and documentation of forest conditions, especially the distribution of nipah plants along with interviews with the local communities. It was known that nipah invasion occurred in the ATPF area due to anthropogenic activities where nipah thrives in open areas, both in tidal and land zones, as well as in pond areas. The invasion of nipah will have an impact on disturbing the balance of mangrove forest ecosystem functions due to changes in the physical, chemical, and biological conditions of the environment. However, nipah has various benefits that can be used by the local community, including the leaves, stems, and fruit, as well as the presence of worms that are associated with the nipah plant.
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Nipa palm (Nypa fruticans) is a coastal invasive species that has depleted many coastal resources across Africa. It is a foreign species that has colonized many coastal areas in both Cameroon and Nigeria. This study involves the investigation of the negative and positive impacts of nipa palm in the waters of Cameroon and Nigeria. These neighboring countries have become endemic for this species in the last 30 years, resulting to a 30% loss of mangrove forest. This loss had led to a decline in the fish population and had caused a safety hazard for boat travelers along the coast. The expansion of the palms beyond local and international boundaries can be controlled through seed removal, tree destruction, seedling monitoring, and establishment of a nipa palm enlightenment and control unit across regional boundaries and a NigeriaCameroon nipa palm management agency, whose aim would be to sensitize the public in both countries regarding the need to stop nipa palm encroachment because of its adverse effect on the ecosystem and livelihood opportunities of rural dwellers. Also recommended is the use of the palm to produce biomass energy.
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It is postulated that the presence of nypa palm ( Nypa palm ) in mangrove forest affect the reproductive function of fish by inhibiting the growth of macro invertebrates. The impact of Nypa fruticans (Wurmb) and mangroves on the benthic macro invertebrate community of Andoni River was carried out between January and August, 2017. A total of four stations were chosen based on nypa palm and native mangrove species’ presence and absence, station 1 (Open water), Station 2 (Nypa palm dominance), station 3 (Rhizophora and Avicennia dominance), Station 4 (Mixed). Results of water quality parameters include; pH 6.99±0.16, Temperature 28.20±0.05°C, DO 4.71±0.18mg/L, Conductivity 19.52±0.20µm/s, Salinity 10.76±0.07ppt, TDS 13.45±0.27ppt. Mean values of the physico-chemical parameters (P > 0.05) were not significantly different. Twelve taxa of benthic macro-invertebrates in eleven families were collected. The crustaceans were more in diversity (38.46%), while bivalvia, pisces and oligochaete had the least percentage composition (7.69%). The gastropods were more in species dominance (44.69%), while the Oligochaeta were least in abundance (0.61%). Shannon Weiner’s index across the stations for benthos was highest in station 2 (1.840) and lowest in station 1 (1.103). Simpson’s index was highest in station 2 (1.990) and lowest in station 1 (1.938). Pielou’s index of evenness was highest in station 2 (0.767) and lowest in station 1 (0.616). All the macro-invertebrates recorded were clean water and pollution tolerant species, and showed no significant difference across stations (P>0.05). In conclusion this study indicates that nypa palm does not affect the proliferation of macro invertebrates, which supports fishery population along the food chain.
Chapter
The Stubbs Creek Forest Reserve (SCFR), which was officially established in 1930, is a biodiversity hotspot containing various ecosystem types, including freshwater, mangrove swamps and beach ridges, which formed a habitat to a variety of flora, fauna and microbes. Biodiversity of the reserve had sustained local communities in the area for decades, especially for the provision of food and edible fruits, water, timber and non-timber forest products, fuelwood, building materials, fibre, medicinal herbs and spices. The reserve is currently being threatened by several factors. Exotic nipa palm that was introduced into the area in the 1900s is fast displacing indigenous mangrove vegetation, not just in the forest reserve alone but in the entire Nigerian coastline. Oil exploration, which started in the area in the 1950s, opened up the area for human encroachment, farming, wood logging, waste disposal and palm wine tapping which is now threatening the survival of the forest reserve. Except urgent steps are taken to control unstainable resource exploitation in the forest reserve, the biodiversity of the area could be destroyed beyond remedy within few years.
Article
The mangrove communities of the Caribbean region are considered descendants of former pantropical Late-Cretaceous mangroves that underwent regional differentiation after the tectonic closure of the Tethys Sea. The southern Caribbean area has been considered the cradle of Neotropical mangroves. These inferences were based mainly on qualitative evidence, such as the presence/absence of fossils showing botanical affinities with present-day mangrove taxa. However, as demonstrated in Quaternary paleoecology, the most suitable approach for reconstructing past plant communities is the assemblage approach, which is based on quantitative palynology. Therefore, the problem of the origin of Caribbean mangroves, as ecological communities, is addressed here by reviewing in detail the Late Cretaceous to Eocene quantitative palynological studies available for the region to properly reconstruct past mangrove assemblages. No evidence has been found for the occurrence of mangrove ecosystems during the Late Cretaceous and the Paleocene, only records of the fossil representatives of some individual taxa (Nypa, Acrostichum), which are not mangrove-forming elements and, hence, are not reliable indicators of mangrove communities. The first robust evidence of true mangrove communities was found in the Middle Eocene (Lutetian). These mangrove communities were dominated by the fossil representative of Pelliciera, a mangrove-forming tree with a Neotropical distribution by that time. Back-mangrove communities were dominated by the palm Nypa (which was pantropical by that time but is now restricted to the Indo-Mayana region), the fern Acrostichum and palms, notably Mauritia, along a sea-land saline to freshwater community gradient. Pelliciera originated in the southern Caribbean during the Early Eocene and became dominant in the Middle Eocene, when it dispersed across the Caribbean area, probably favored by the migration of the Caribbean plate. Therefore, the first Caribbean mangroves were ecological and evolutionary innovations that emerged de novo during the Middle Eocene, rather than a consequence of the regional evolutionary differentiation from hypothetical Late Cretaceous Tethyan mangroves, whose existence is not supported by quantitative palynological records. It is proposed to develop this type of study for other tropical/subtropical mangrove communities, for a sounder view of mangrove origin and evolution, at a global scale.
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Mangroves of the Niger Delta are the largest in Africa and are the source of numerous ecosystem services such as firewood, seafood, building materials and medicinal herbs. Their sustainable use and protection are important for future generations. However, anthropogenic activities such as oil and gas exploration, urbanization , industrialization, dredging, overexploitation and sand mining are the major disturbances that have pushed the mangroves to the brink of extinction. Therefore, in other to restore lost areas of the mangroves natural and artificial means can be adopted to bring them to a restored state. More often than not emphasis of recovery had been placed on artificial remediation and restoration, where polluted sites are cleaned with chemicals and nursery seedlings transplanted to remediated such sites. Nevertheless, this chapter discusses the possibility of utilizing natural means of forest recovery through seedling recruitment and regeneration. This can be achieved by establishing the right environmental conditions such as setting up of a hydro-channel to ensure smooth inflow and out flow of river water carrying seeds, availability of parent mangrove trees to supply the seeds, and the availability of the right soil condition to enable seedling germination and growth. The use of dried and ground mangrove parts as a new way for restoring polluted soil is discussed; in addition, the unconventional proposition of using low key pollution to manage and increase forest resilience is highlighted in this work even though further studies are recommended. Future direction of mangrove restoration should be tilted towards the application of the force of nature, which has the potentials of reversing the adverse effect of anthropogenic activities in well managed and protected sites.
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Years of oil and gas exploration and spread of exotic nypa palm has converted the mangroves into a disturbed system. It is hypothesized that polluted soils will have adverse effect on the growth of mangrove and Nypa palm seedlings. This hypothesis was tested using a reciprocal transplant experiment on soils with different levels of pollution. Soil and seed samples were collected in-situ, cross-planted and monitored for sixteen months. Stem diameter, height of seedling, number of leaves and number of leaf scars was measured and survivorship curves plotted. We found that for mangroves the source of the soil had a significant effect on height, but no effect on diameter and number of leaves. Furthermore, the source of the seed had effect on both the height and the number of leaves. Both the soil-and the seed-source had no effect on leave scars, even though more scars were found on mangrove grown in highly polluted soil than on mangroves grown in lowly polluted soil. We found that for nypa palm both soil-and seed-source had effect on height and number of leaves, but had no effect on diameter. Mangrove propagules grown in lowly polluted soil had higher survival than those grown in highly polluted soil. Nypa palm seedlings had higher survival rate than mangrove propagule. Thus, pollution had little effect on seedling growth within species, but had effect across species.
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The Niger Delta mangrove is the third largest in the world and the largest in Africa. Since the 1960s oil and gas exploration has become an important economic activity, resulting in significant alteration of the landscape via pollution, urbanization and invasion. Landsat images of six different years (1984, 1986, 2000, 2003, 2005 and 2007) were used to determine land cover across 3, 700 km2. Landscape was segregated between areas with oil and gas exploration and those without. Two forest types were identified namely mangrove and mixed, which were further decomposed into high (Mang 1) and low (Mang 2) density mangroves and palms. A total of 145 landscape square samples, each 6.76 km2 were randomly selected in each map and statistically analyzed and modeled. The results showed that the kappa coefficient for the six years were all >0.9, (i.e., 0.93, 0.07, 0.94, 0.93, 0.90 and 0.94) indicating high classification accuracy. Also great change in mangrove landscape occurred in the last decade. Locations with increased oil and gas activities had significantly decreased amount of mangrove and palm forests. Also mixed forests increased over time and had a significant negative relationship with mangrove, Mang 1 and Mang 2. Even though the total area of mangrove forest did not change significantly (p>0.05), the total biomass of mangrove decreased (p<0.01). Nypa palm abundances increased over time, yet, it is negatively affected by the exploration. Increase in mixed forest and urban region has negatively affected the mangrove forest in the Niger’s delta landscape. High density mangrove forest withstood better the impacts of oil and gas exploration compared to mixed forest, but low density mangrove forest was the opposite. This suggests complex landscape level effects among different forest types.
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Nutrient cycling often moves between litter fall and decomposition. It is hypothesized that hydrocarbon pollution will slow down mangrove litter decomposition because of the reduction in microbial activities. We studied decomposition rates at different levels of pollution (i.e. high and low) and amongst different mangrove species (i.e. red, white and black). For the first experiment, fresh leaves of Rhizophora racemosa were collected, sealed in a litter bag and placed on the mangrove floor for 1.24 years at which all the leaves had completely decomposed to humus and were oven-dried and weighed to calculate the decomposition rate constant (k) of mass loss. Although there was no significant difference in the rate of decomposition (P > 0.05), leaves at the highly polluted plot had lower rate of decomposition (6.58 × 10⁻⁴) when compared to leaves at the lowly polluted plot (1.75 × 10⁻³). In the second experiment, there was a significant difference in decomposition rates amongst species (P < 0.05). Red mangrove leaves (0.41) decomposed more than white (0.28) and black (0.28) mangrove leaves. This implies that hydrocarbon pollution slowed, but did not stop the decomposition of mangrove leaves.
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The Niger Delta, the largest river delta on the African continent, is one of the most densely populated river deltas globally and hosts the world’s third largest mangrove forest. It is a major biodiversity hot spot of our planet. At the same time the delta is home to Africa’s largest oil reserves and responsible for a skyrocketing GDP development of Nigeria since the 1970s. Nigeria ranks 13th among all oil producing countries, but oil exploitation also brought with it severe environmental degradation, leading to the delta’s nomination for a place on the top 10 list of the “World’s Worst Polluted Places Report” in 2013. Despite the outstanding importance of the region for Nigeria, Africa, and the international community most studies published focus mainly on topics of geology, geochemistry, and environmental toxicology. Studies employing earth observation satellite data to assess Niger Delta dynamics are rare. This paper aims at contributing to an overview of Niger Delta geography and environmental threats and challenges, as well as to an understanding of Niger Delta land surface dynamics from 1986 to 2013. Covering the complete delta, we present results of land cover change analyses, results of an assessment of coastline dynamics, as well as the manifestation of oil exploitation activity as expressed via oil access canal dredging and gas flaring, monitored within the 27 year time span investigated.
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1. Human activity is an increasingly important mechanism of plant dispersal, particularly in densely populated countries such as England. We investigated which species are commonly dispersed by the following vectors: (i) soil carried on motor vehicles, (ii) topsoil, (iii) sugar factory topsoil, (iv) horticultural stock, and (v) garden throw-outs. 2. We compared the ecological traits of the species associated with each vector with those of a representative sample of the regional flora. Traits examined were life history, canopy height, lateral spread, flowering start, flowering period, seed persistence in the soil, vegetative reproduction, wind dispersal, log seed weight and specific leaf area. 3. We identified two major anthropogenic dispersal pathways, each associated with a clearly defined group of species. Species associated with topsoil, cars and horticulture depend essentially on soil movement, and are often small and fast-growing, but their most consistent unifying characteristic is the production of numerous, small, persistent seeds. In contrast, garden throw-outs, which are themselves functionally similar to increasing garden escapes, tend to be tall, spreading perennials with transient seed banks, attributes which are almost the exact opposite of the soil-borne group. 4. Some recent studies of the British flora have failed to find any dispersal-related differences between those species with increasing or decreasing ranges, or between natives and invasive aliens. Others have found contradictory attributes of aliens; they were more likely to have bigger seeds than natives, but also more likely to have a persistent seed bank. These findings are consistent with the suggestion that there exist two contrasting groups of successful alien invaders: tall, spreading competitors and small, short-lived, fast-growing species with high reproductive outputs. The parallel with the two groups of species identified here is remarkable, and is further evidence of the probable importance of anthropogenic dispersal in the modern landscape.
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Some theories and experimental studies suggest that areas of low plant species richness may be invaded more easily than areas of high plant species richness. We gathered nested-scale vegetation data on plant species richness, foliar cover, and frequency from 200 1-m2 subplots (20 1000-m2 modified-Whittaker plots) in the Colorado Rockies (USA), and 160 1-m2 subplots (16 1000-m2 plots) in the Central Grasslands in Colorado, Wyoming, South Dakota, and Minnesota (USA) to test the generality of this paradigm. At the 1-m2 scale, the paradigm was supported in four prairie types in the Central Grasslands, where exotic species richness declined with increasing plant species richness and cover. At the 1-m2 scale, five forest and meadow vegetation types in the Colorado Rockies contradicted the paradigm; exotic species richness increased with native-plant species richness and foliar cover. At the 1000-m2 plot scale (among vegetation types), 83% of the variance in exotic species richness in the Central Grasslands was explained by the total percentage of nitrogen in the soil and the cover of native plant species. In the Colorado Rockies, 69% of the variance in exotic species richness in 1000-m2 plots was explained by the number of native plant species and the total percentage of soil carbon. At landscape and biome scales, exotic species primarily invaded areas of high species richness in the four Central Grasslands sites and in the five Colorado Rockies vegetation types. For the nine vegetation types in both biomes, exotic species cover was positively correlated with mean foliar cover, mean soil percentage N, and the total number of exotic species. These patterns of invasibility depend on spatial scale, biome and vegetation type, spatial autocorrelation effects, availability of resources, and species-specific responses to grazing and other disturbances. We conclude that: (1) sites high in herbaceous foliar cover and soil fertility, and hot spots of plant diversity (and biodiversity), are invasible in many landscapes; and (2) this pattern may be more closely related to the degree resources are available in native plant communities, independent of species richness. Exotic plant invasions in rare habitats and distinctive plant communities pose a significant challenge to land managers and conservation biologists.
Book
People of European descent form the bulk of the population in most of the temperate zones of the world - North America, Australia and New Zealand. The military successes of European imperialism are easy to explain; in many cases they were a matter of firearms against spears. But as Alfred W. Crosby maintains in this highly original and fascinating book, the Europeans’ displacement and replacement of the native peoples in the temperate zones was more a matter of biology than of military conquest. European organisms had certain decisive advantages over their New World and Australian counterparts. The spread of European disease, flora and fauna went hand in hand with the growth of populations. Consequently, these imperialists became proprietors of the most important agricultural lands in the world. In the second edition, Crosby revisits his now classic work and again evaluates the global historical importance of European ecological expansion.
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3 Abstract: In a study to assess the impact of dredging on heavy metal contamination, surface water was monitored for over one year, from December 1997 to December 1998. Samples were collected twice before dredging, in December 1997 and in June 1998, corresponding to dry and raining seasons respectively. Samples were also collected immediately after dredging in July 1998 and were monitored in August, September and December 1998. Samples were collected analysed from five stations within the study area, station 1-5. Station 1 was in the dredged canal, which was originally a side branch of the Warri River tributary. In the Warri River tributary, Station 2 was 500m upstream and Station 3 was 1000m upstream of the mouth of the dredged canal, whilst Stations 4 and 5 were respectively 500m and 1000m downstream of it. Stations 3 and 5 represented the reference situation to which possible dredging effects could be compared. Prior to dredging, the concentration of heavy metals in the surface water samples of Warri River occurred in traces; lead (0.01-0.28 mg l̄ ), 1 zinc (0.04-1.02 mg l̄), copper (0.00-0.17 mg l̄), iron (0.22-0.88 mg l̄), chromium (0.00-0.03 mg l̄) and cadmium 1 1 1 1