Avicennia+alba

**//Avicennia alba// (Blume, 1826)** **Api-Api Putih**

=General Introduction = toc //Avicennia alba// is a common species of mangrove plant that belongs to the family Acanthaceae. It has a common name Api-api putih, in the Malay language¹. It is prominently characterised by its elongated and pointed leaves that are coloured darker green on the upperside and paler, whitish on the underside. Api-api putih commonly exists in the front zone area of a coastal swamp forest (i.e. area that is closest to the sea).

'Avicennia' is said to honour Iranian philosopher and physician, Avicenna (980-1037)². ‘Api’ means ‘fire’ in Malay and it originates from the observation that this particular mangrove attracts fireflies. ‘Putih’ and ‘alba’ means ‘white’ in Malay and Latin respectively and it is from the fact that the leaves are pale-coloured on the underside.
 * Etymology **

**Class:** Magnoliopsida **Order:** Lamiales **Family:** Avicenniaceae **Genus:** //Avicennia// **Species:** //alba//
 * Taxonavigation **

=Distribution = Api-api putih has a wide distribution from Western India to Indochina, the Malay Archipelago, the Philippines, New Guinea and Northern Australia (Figure 1)³.
 * Global distribution **



This particular species is very common in Singapore and can be found in almost all the mangrove patches in Singapore, as seen in Figure 2. The map below shows the distribution of mangrove forest in Singapore and the places **<span style="color: #ff0000; font-family: 'Times New Roman',Times,serif; font-size: 130%;">bold in red **<span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;"> are mangroves where Api-api putih can be found, with information gathered from various online sources⁴. <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">If you want to visit a mangrove in Singapore, there are four that are accessible to the public! <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">1) Sungei Buloh Wetland Reserve; <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">2) Chek Jawa; <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">3) Pasir Ris Mangrove and; <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">4) Berlayer Creek <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Visit [|National Parks Board] website for directions! <span style="display: block; font-family: 'Times New Roman',Times,serif; font-size: 17px; text-align: right;">Back to Top
 * <span style="color: #2b60de; font-family: 'Times New Roman',Times,serif; font-size: 150%;">Distribution within Singapore **

=<span style="color: #0000a0; font-family: 'Times New Roman',Times,serif; font-size: 150%;">How to identify Api-api putih! = <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Api-api putih is a tree that can grow up to around 10 to 25 metres in height. With the description of the plant below, you can learn how to identify Api-api putih as well³! <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">-Characteristically lanceolated (long and pointed at the apex) <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">-Around 8-12cm long <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">-Dark green on upperside, pale-coloured, whitish on the underside <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">-Leaves are simple (undivided leaf blade) and opposite (a pair of leaves attached at a node)
 * **<span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">Leaves **

|| <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">- Orange-yellow colour with around 10-30 flowers on each unit. <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">- Each flower is only about 0.5cm in diameter with four equal lobed petals that are smooth on the inside. <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">- Flowers of Api-api putih is distinguished from other //Avicennia// species by its long spicate distal flower units that are about 1.5 to 3cm long. <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">- Stamens are short, only about 2mm long and does not protrude or thrust outwards <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">- Ovary is about 2mm long and without a style. || <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">- Distinctive conical shape that extends to a pronounced pointed tip. <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">- It is especially obvious during the early stages of fruit development. <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">- About 1-4cm long <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">- Smooth velvety outer skin. <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">- Each fruit contains a single seed. || - About 20–30 cm tall with a tapered bluntly pointed end. - Lenticels, for gaseous exchange, are found on the roots. || <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">- Somewhat dark grey/brown. <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">- Smooth or slightly roughened but it is not fissured. <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">- A distinct character of Api-api putih tree is the growth of sooty mould on older stem parts. || <span style="display: block; font-family: 'Times New Roman',Times,serif; font-size: 17px; text-align: right;">Back to Top
 * **<span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">Flowers **
 * **<span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">Fruits **
 * [[image:alba roots.jpg width="495" height="374" align="left" caption="Pencil roots growing upwards to a height of around 20 to 30cm. (Source: Cheong J. M. D)"]] **<span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">Roots ** <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">- Pencil-like aerial roots known as pneumatophores.
 * **<span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;"> Bark **

=<span style="color: #0000a0; font-family: 'Times New Roman',Times,serif; font-size: 170%;">Biology =

**<span style="color: #2b60de; font-family: 'Times New Roman',Times,serif; font-size: 150%;">Habitat type **
<span style="display: block; font-family: 'Times New Roman',Times,serif; font-size: 130%; text-align: left;">Api-api putih is known to be a pioneering species, meaning they are able to quickly colonise areas which are previously damaged. A typical zonation pattern in the Indo-Pacific region is one with //Avicennia// species to be nearest to the coastline (seaward side) on newly-formed mud banks⁵ and //Avicennia// species. are known to be able to thrive in habitats with higher salinity and silt⁶. Nonetheless, one should keep in mind that there is no universal pattern of zonation in a mangrove forest because zonation is driven by combinations of external factors acting on the locality⁷, including substrate types, hydrodynamic forces, inundation regime and propagules sorting⁸.

**<span style="color: #2b60de; font-family: 'Times New Roman',Times,serif; font-size: 150%;">Reproduction **
<span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Api-api putih, like all other //Avicennia// species are **i****nsect-pollinated**. They are commonly pollinated by flies and bees. These pollinators serve an important purpose for successful sexual reproduction for greater genetic variability because Api-api putih is capable of self-pollination⁸<span style="font-family: arial,helvetica,sans-serif; font-size: 13px; line-height: 1.5;">. Although flowers of Api-api putih are very similar to flowers of //Avicennia marina// and //Avicennia officinalis,// studies showed that their flowering time is non-synchronised to minimise competition for pollinators and spread availability of nectar over a longer period of time⁹<span style="font-family: arial,helvetica,sans-serif; font-size: 13px; line-height: 1.5;">.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">After pollination, Api-api putih **reproduces via** **cryptovivipar**y. This means that t <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%; line-height: 1.5;">he single seed does not remain dormant in the fruit but actively produces chlorophyllous seedling within the fruit⁹, <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%; line-height: 1.5;">without breaking through the fruit wall¹⁰. <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">When the fruit detaches from the parent plant, <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 25.3500003814697px;">seedling will burst through the fruit wall and are **<span style="font-family: 'Times New Roman',Times,serif; font-size: 130%; line-height: 1.5;">dispersed by water. ** <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%; line-height: 1.5;">Each tree produces numerous seedlings which are <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 25.3500003814697px;">small and light to remain buoyant and are dispersed widely via <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%; line-height: 1.5;">tidal currents though establishment of seedlings remained mainly along the coastline⁹. As seedlings are chlorophyllous, they can photosynthesise as soon as they take root.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 130%; line-height: 1.5;">For s <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px;">uccessful establishment of seedlings, a ‘window of opportunity’ is required where disturbance (such as tide level, erosion rate, weather conditions) is at minimum¹¹. Figure 3 below shows the three challenges that an Api-api putih seedling needs to overcome for successful establishment. 1) Seedlings need to grow a minimum root length during an inundation-free period to prevent floating during a tidal inundation; 2) after which, roots need to be long enough to resist against hydrodynamics forces of waves and currents; and lastly 3) when roots penetrate into the sediments, it has to resist sediment erosion to prevent being dislodged¹¹.



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=<span style="color: #0000a0; font-family: 'Times New Roman',Times,serif; font-size: 170%;">Ecology = || || <span style="display: block; font-family: 'Times New Roman',Times,serif; font-size: 17px; text-align: right;">Back to Top ||
 * ~ <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">Damage/Pest ||~ <span style="font-family: 'Times New Roman',Times,serif; font-size: 150%;">Mechanism/Organism ||
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Avicennia seed moth //Autoba alabastrata¹²// || * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">This is the most serious pest related mortality on mature fruits of Api-api putih.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Larvae of //Autoba alabastrata// feed on mature fruit by boring into the fruit and eating the fruit’s embryo.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Infected fruit will be attached to a nearby stem by a web produced by larvae.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">This prevents fruit from falling into the water when it detaches from the parent tree because larvae would drown if water floods into the fruit via large bore holes. [[image:taxo4254/seed moth2.jpg width="120" height="196" align="right" caption="Large bore holes on fruit (Source: Guide to the mangroves of Singapore)"]]
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%; line-height: 1.5;">Each larva is capable of destroying up to eight fruits before it pupates in the last fruit.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%; line-height: 1.5;">An infected tree is easily identified by its shrivelled fruits.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Foliage damage by herbivores //<span style="font-family: 'Times New Roman',Times,serif; font-size: 17px;">¹² // || * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">All //Avicennia// species are often damaged by leaf mining moth //Phyllocnistis// which will destroy young leaves by mining the upper surface of young expanding leaves.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">They then pupate in a fold at the edge of the leave.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Structural damage //<span style="font-family: 'Times New Roman',Times,serif; font-size: 17px;">¹² // || * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Twigs and young stems of young //Avicennia// species saplings are susceptible to twig boring larvae of Cossidae moth (//Zeuzera conferta//).
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">The larva bore through the pith canal and causes nodular enlargement.

=<span style="color: #0000a0; font-family: 'Times New Roman',Times,serif; font-size: 170%;">Adaptations = <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px;">Api-api putih are usually found near the coast and its habitat is frequently inundated. Therefore, it has special adaptations to survive in areas that have high salinity, waterlogged muddy soil and high wave actions¹³.

**<span style="color: #2b60de; font-family: 'Times New Roman',Times,serif; font-size: 25px;">Roots **
<span style="font-family: 'Times New Roman',Times,serif; font-size: 17px;">During a tidal inundation, waterlogged soils are often poorly oxygenated. Therefore, Api-api putih has specialised roots, also known as breathing roots, to help in gaseous exchange. These roots are vertical pencil roots, known as pneumatophores, which grows vertically upwards from the submerged lateral underground root system (Figure 5). Pencil roots are covered with lenticels that enables gaseous exchange for oxygen directly from the surface (Figure 4). Hence, pencil roots provide the plant with additional oxygen which cannot be taken from the soil. However, gaseous exchange can only occur when pencil roots are not submerged because at high tides, surface tension of water blocks lenticels and prevent gaseous exchange¹⁴. <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 1.5;"> Therefore, permanent inundation in the mangrove habitat will eventually kill the root system and the plant. <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 1.5;">Pencil roots and underground lateral root system (Figure 5) spread over large areas which help to stabilise tree on the unstable waterlogged ground as well as to withstand high wave actions. Additionally, extensive pencil roots network help to stabilize the sediments and prevent erosion.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 18px;">Vertical pencil roots (pneumatophores) help to transport oxygen to underground root system **<span style="font-family: 'Times New Roman',Times,serif; font-size: 17px;">¹⁴.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 18px;">Increases stability of tree **



<span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 1.5;">Mangroves evolved specialised survival strategies to thrive under high salinity environments. For //<span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 1.5;">Avicennia //<span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 1.5;"> species, they are salt secretor, which means that they exclude excess salt from their roots and leaves. The roots exclude 85-95% of the salt that are carried towards the roots via transpiration. This is because roots develop barriers against apoplastic movement that increase resistance to water flow and exclude salt from entering the roots¹⁵. This helps to maintain salt concentration balance within the whole plant. <span style="color: #2b60de; font-family: 'Times New Roman',Times,serif; font-size: 25px; line-height: 1.5;">**Salt secretion from leaves** <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px;">Api-api putih, like other //Avicennia// species, secretes excess salt that is not excluded at the roots from its leaves <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 25.3500003814697px;">¹⁶ <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 1.5;"> (Figure 6). Salts are expelled through specialized salt-secreting glands which are small slit-like openings found on the upper surface of the leaves¹⁷ ¹⁸. This further regulates salt concentration in the plant.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 18px;">Important for salt exclusion **

<span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;"> **Fast root and seedling developmen** **t** <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">From information mentioned in the section on Reproduction, Api-api putih is known to have fast root and seedlings development. These are essential to anchor seedlings into sediment and survive against wave action¹¹ and to start photosynthesising as soon as seedling take root, to grow quickly. These adaptations make Api-api putih a good coloniser of bare tidal flats.

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=<span style="color: #0000a0; font-family: 'Times New Roman',Times,serif; font-size: 31px; line-height: 1.5;">Conservation status = <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px;">Despite the threats listed above, Api-api putih has a conservation status of being the least concern, according to the IUCN Red list¹⁹. This species is widespread (as seen in Figure 1), although it is still threatened by the loss of mangrove habitats.

=**<span style="color: #0000a0; font-family: 'Times New Roman',Times,serif; font-size: 31px;">Taxonomy **= <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px;">The original description of Api-api putih is in Latin by Blume C.L.(1826) [|Bijdragen tot de flora van Nederlansch Indië Vol. 14: 821.]
 * <span style="color: #2b60de; font-family: 'Times New Roman',Times,serif; font-size: 20px;">Original description **



<span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">From the description above, it roughly translates to:

<span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">'Leaves are oblong-lanceolate and acute, smooth snowy underside. It increases towards the shore. Flowers blossoms all year-round and the name is Api Api' <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px;">The [|type] specimen of Api-api putih can be found in Botanic Garden Meise Herbarium in Belgium (Barcode number: BR0000009088016). <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px;">One can refer to this type specimen (Figure 7) to confirm the identification of Api-api putih plant. = = <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px;">In the genus //Avicennia// L., there are eight species. From a study by Schwarzbach and McDade (2002)²⁰ to find the phylogenetic relationship of mangrove family Avicenniaceae with analysis using chloroplast and nuclear ribosomal DNA sequence, <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 25.5px;"> four //<span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 25.5px;">Avicennia //<span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 25.5px;">species was sampled, and //<span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 1.5;">Avicennia //<span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 1.5;"> was found to be strongly monophyletic as shown in Figure 8 below.
 * <span style="color: #2b60de; font-family: 'Times New Roman',Times,serif; font-size: 20px;">Type Information **
 * <span style="color: #2b60de; font-family: 'Times New Roman',Times,serif; font-size: 20px;">Phylogenetic analysis **



<span style="font-family: 'Times New Roman',Times,serif; font-size: 17px;">In another <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 25.5px;">study by Ghose et al. (2014)²¹, a random amplified polymorphic DNA (RAPD) analysis was conducted on three species of //Avicennia,// //<span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 1.5;">Avicennia alba //<span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 1.5;"> (Api-api putih), //<span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 1.5;">Avicennia marina //<span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 1.5;"> (Forsk.) Vierh. and //<span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 1.5;">Avicennia officinalis //<span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 1.5;"> L. <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px;">As molecular markers are not affected by environmental factors, unlike morphological markers, DNA markers can be used to quantify interspecific genetic diversity and establish phylogenetic relationships among species²¹.
 * <span style="color: #2b60de; font-family: 'Times New Roman',Times,serif; font-size: 20px;">Genetic studies to help improve efficiency of breeding programmes **

<span style="font-family: 'Times New Roman',Times,serif; font-size: 17px;">From the study, results showed that:
 * 1) <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px;">//A. alba// and //A. officinalis// are more closely related to each other and share a common mode on the phylogenetic tree at 73.4% of similarity (Figure 9).
 * 2) <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px;">//A. marina// showed most genetic variability.

<span style="font-family: 'Times New Roman',Times,serif; font-size: 17px;">Therefore, this suggests that //A. marina// should be used over other species in breeding programmes to conserve genetic variability which are needed for species to have higher fitness and have the ability to adapt, evolve and prevent extinction. Genetic studies can help in improving the understanding of phylogenetic relationships, which may further assist breeding programmes for sustainable management and conservation of genetic resources. <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">There are no evidence of hybridization among different species of //Avicennia//, even if more than one species are found in close proximity to one another, thus demonstrating their reproductive isolation²². <span style="display: block; font-family: 'Times New Roman',Times,serif; font-size: 17px; text-align: right;">Back to Top
 * <span style="color: #2b60de; font-family: 'Times New Roman',Times,serif; font-size: 20px;">Hybridization in //Avicennia// species **

=<span style="color: #0000a0; font-family: 'Times New Roman',Times,serif; font-size: 170%;">Importance of Mangroves = <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Other than Api-api putih, there are many other species of mangrove plant. In fact, that are roughly 70 species of mangroves around the world²². Mangroves are valuable ecology and economic resource, providing humans and other organisms with many goods (e.g. wood for fuel, food items) and ecosystem services (e.g. coastal protection, flood abatement) <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px;">²³ <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">. Read on to find out more about the importance of mangroves!


 * <span style="color: #2b60de; font-family: 'Times New Roman',Times,serif; font-size: 170%;">General importance **
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">1) They are ‘land builders’ **<span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">²⁴
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Mangroves roots help to trap sediments and reclaim land naturally. Trapping of sediments also contribute to soil formation which also facilitates in stabilizing the coastline²⁵.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">2) Natural water purification system **
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Mangroves act as a filter for upland run-off via trapping of sediments and litters between their network of roots²⁶ (Figure 10). This helps to prevent sediments and litters from being flushed into the sea and cause marine pollution.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Filtration of water improves water quality and maintain water clarity which are important for organisms like clams and oysters to thrive in the mangrove and intertidal area²⁶.


 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">3) Nursery for juvenile organisms **
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Mangroves serve as important nurseries for juvenile of many marine organisms, such as reef fishes, crabs and oysters²⁷ ²⁸, by providing food and shelter against predators before juveniles grow big enough to swim out to patch reefs or the ocean²⁹.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">They are also important feeding grounds for transient birds, reptiles and fishes²⁵.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">4) Contribution to marine productivity **
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Mangroves produce large amounts of detritus that serves as the basis of the food web and hence possibly contributes to productivity in offshore waters²⁶.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 140%; line-height: 25.3500003814697px;">5) Carbon sequestration **
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 17px; line-height: 25.3500003814697px;">Mangrove forests are is one of the largest storage of carbon³⁰. Thus they play an important role in the global carbon cycle. Therefore, increasing the extent of mangrove forests can be used as effective means against climate change.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">6) Coastline protection **
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Mangroves are found along coastlines and they serves as a barrier of protection against shoreline erosion by strong waves and currents and help to protect coastal communities against storms²⁵.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">From Figure 11, it shows that wave height can be reduced as it travels through the mangrove forest. For example, wave height is reduced by 35% as it travels through 80 metres of mangrove forest³¹.


 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">7) Contribute nutrient to environment **
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">//Avicennia// species have leaves that are known to be thinner and contain fewer types of tannin (less chemical defense against herbivory). Therefore they decomposed at a faster rate than other mangrove species³², contributing more nutrient to the environment.
 * <span style="color: #2b60de; font-family: 'Times New Roman',Times,serif; font-size: 170%;">Importance of mangrove in Singapore **
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">Important feeding ground for migratory birds³³ **
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">An important mangrove habitat in Singapore is Sungei Buloh Nature Reserve which serves as a major bird roosting site. Every year, Sungei Buloh function as an important stop-over site for around 12 – 15 thousand million migratory birds flying from the northern Eurasian continent to Africa and the Southern parts of Asia to escape the winter months. The flyway (migratory route) along Singapore is known as the East Asian Australasian Flyway. <span style="display: block; font-family: 'Times New Roman',Times,serif; font-size: 17px; text-align: right;">Back to Top

=<span style="color: #0000a0; font-family: 'Times New Roman',Times,serif; font-size: 170%;">Threats to Mangroves = <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Despite the importance of mangroves, this ecosystem still faces threats which have the potential of pushing some species to extinction.


 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">1) Conversion of mangrove forest for shrimp farming **
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%; line-height: 1.5;">Due to the high biomass productivity in the mangrove forest, trees are often cleared away for conversion into shrimp ponds (Figure 12). In the past, Sungei Buloh also had shrimp ponds where prawns spawn in the mangroves that were rich in organic nutrients³⁴. However, shrimp aquaculture has many harmful impacts on the mangrove forest, including direct loss of mangrove forest to construct ponds, increase in sedimentation and turbidity from ponds, reduction in water quality and influx of excess nutrients which could lead to harmful algal bloom²³.




 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 140%; line-height: 1.5;">2) Overexploitation of ecological goods and services **
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Mangrove forest has long been exploited by coastal communities for its ecological goods such as timber, tannin and food, and services such as water filtration and flood abatement. The increase in human population has led to encroachment of community into coastal area. This may results in increased volume of waste being dumped into mangroves and adjacent coastal habitats. While mangrove forest can adsorb some of the excess nutrients, toxic waste are harmful to their growth³⁵.
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">3) Mangrove deforestation **
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Mangrove forests are also deforested for timber as well as to make space for growing agriculture crops, building of housing or for aquaculture (Figure 13). Sediments usually get accumulated at flooded estuaries and mangrove forests.When mangroves are removed, the loss of a sediment sink may lead to increase sediments in the sea³⁶.




 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 140%;">4) Coastal squeeze **
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Mangrove forests are vulnerable to sea level rise and they progress landwards at a rate that is determined by the rate of 1) sea level rise, 2) sediment accretion and 3) rate of erosion²³. However, as countries build seawalls against sea level rise, they prevent migration of mangroves toward adjacent upland³⁷ (Figure 14). Coastal squeeze will slowly decrease the area of mangrove forest and eventually causing them to drown if sediment erosion by sea level rise is greater than sediment accretion³⁷.



<span style="display: block; font-family: 'Times New Roman',Times,serif; font-size: 17px; text-align: right;">Back to Top

=<span style="color: #0000a0; font-family: 'Times New Roman',Times,serif; font-size: 31px;">Glossary = <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Here are definitions of some of the terms used in the page to help you better understand the content³⁹!

<span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Apex: The tip or point. <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Spicate: Arranged in spikes <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Fissured: Narrow opening produced by cleavage, to split. <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Lenticels: A body of cells formed on the outer layer of woody stems and roots, appearing as a lens-shaped spot and serving as a pore. <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Chlorophyllous: of or containing chlorophyll for photosynthesis. <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Inundation: To flood; cover or overspread with water <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Apoplastic movement: Movement of water and solutes through the cell walls and intercellular space, without crossing the plasma membrane. <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Hybridization: To produce hybrids which is the offspring of two different species, breeds or varieties. <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Detritus: organic matter produced by the decomposition of organisms. <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">Encroachment: To advance beyond proper or usual limits. <span style="display: block; font-family: 'Times New Roman',Times,serif; font-size: 17px; text-align: right;">Back to Top

=<span style="color: #0000a0; font-family: 'Times New Roman',Times,serif; font-size: 170%;">Contact me = <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%; line-height: 0px; overflow: hidden;">Do feel free to contact me at jesstay92@gmail.com if you wish to use any of the photos which are taken by me ( <span style="font-family: 'Times New Roman',Times,serif; font-size: 130%;">source: © Jessica Tay) or you have any questions regarding the page. Also, please check out the other species pages that were done by other students who have taken this module!

=<span style="color: #0000a0; font-family: 'Times New Roman',Times,serif; font-size: 170%;">References = <span style="font-family: 'Times New Roman',Times,serif;">[1] Ng P.K.L and Sivasothi N. (1999). A Guide to the Mangroves of Singapore I: The Ecosystem and Plant Diversity. Singapore Science Centre. <span style="font-family: 'Times New Roman',Times,serif; line-height: 1.5;">[ <span style="font-family: 'Times New Roman',Times,serif; line-height: 1.5;">2] Umberto Q. (2000). CRC World dictionary of plant names: Common names, scientific names, eponyms, Synonyms and etymology. Volume 1 A-C. CRC Press, 1999. pp. 242. <span style="font-family: 'Times New Roman',Times,serif;">[3] Tomlinson P. B. (eds). (1994). The botany of mangroves. Cambridge tropical ecology series. Cambridge university press. pp. 419. Tomlinson, B. P., 1986. The Botany of Mangroves. Cambridge University Press, Cambridge <span style="font-family: 'Times New Roman',Times,serif;">[4] Yee A.T.K., Ang W.F., Teo S., Liew S.C., Tan H.T.W. (2010). The present extent of mangrove forest in Singapore. Nature in Singapore 3:139–145. <span style="font-family: 'Times New Roman',Times,serif;">[5] Smith T.J.III. (1992). Forest structure. In: Robertson AI, Alongi DM (eds) Tropical mangrove ecosystems. American Geophysical Union. American Geophysical Union, Washington, pp 101–136. <span style="font-family: 'Times New Roman',Times,serif;">[6] El-Khouly A.A. and Khedr A.A. (2007). Zonation pattern of Avicennia marina and Rhizophora mucronata along the red sea coast, Egypt. World applied sciences journal 2:283–288. <span style="font-family: 'Times New Roman',Times,serif;">[7] Lugo A.E. and Snedaker S.C. (1974). The ecology of mangroves. Annual review of ecology and systematics 5:39–64. <span style="font-family: 'Times New Roman',Times,serif;">[8] Matthijs S., Tack J., van Speybroeck D. and Koedam N. (1999). Mangrove species zonation and soil redox state, sulphide concentration and salinity in Gazi Bay (Kenya), a preliminary study. Mangroves and salt marshes 3: 243–249. <span style="font-family: 'Times New Roman',Times,serif;">[9] Raju A.J.S., Rao P.V.S., Kumar R. and Mohan S.R. (2012). [|Pollination biology of the crypto-ciciparous Avicennia species (Avicenniaceae)]. Journal of threatened taxa 4:3377–3389. <span style="font-family: 'Times New Roman',Times,serif;">[10] Ong J.E. and Gong W.K. (2013). [|Structure, function and management of mangrove ecosystems. ISME mangrove educational book series]No. 2. International society for mangrove ecosystems (ISME), Okinawa, Japan, and International Tropical Timber Organisation (ITTO), Yokohama, Japan. <span style="font-family: 'Times New Roman',Times,serif;">[11] Balke T., Bouma T.J., Horstman E.M., Webb E.L., Erftemeijer P.L.A. and Herman P.M.J. (2011). [|Windows of opportunity: thresholds to mangrove seedling establishment on tidal flats]. Marine ecology progress series 440:1–9. <span style="font-family: 'Times New Roman',Times,serif;">[12] Murphy D.H. (1990). [|The natural history of herbivory on mangrove trees in and near Singapore.] Raffles Bulletin of Zoology 38:119–203. <span style="font-family: 'Times New Roman',Times,serif; line-height: 1.5;">[ <span style="font-family: 'Times New Roman',Times,serif; line-height: 1.5;">13] Joshi H. and Ghose M. (2003). [|Forest structure and species distribution along soil salinity and pH gradient in mangrove swamps of the Sundarbans]. Tropical ecology 44:197–206. <span style="font-family: 'Times New Roman',Times,serif;">[14] Mangrove roots (2014). Retrieved from: []. (Accessed on 18th October 2014) <span style="font-family: 'Times New Roman',Times,serif;">[15] Krishnamurthy P., Jyothi-Prakash P.A., Qin L., He J., Lin Q., Loh C., and Kumar P.P. (2014). Role of root hydrophobic barriers in salt exclusion of a mangrove plant //Avicennia officinalis.// Plant, Cell and Environment. <span style="font-family: 'Times New Roman',Times,serif;">[16] Parida A.K. and Jha B. (2010). Salt tolerance mechanisms in mangroves: a review. Trees 24:199–217. <span style="font-family: 'Times New Roman',Times,serif;">[17] Shimony C., Fahn A. and Rheinhold L. (1973). Ultrastructure and ion gradients in the salt glands of //Avicennia marina// (Forsk) Vierh. The New Phytologist 72:27–36. <span style="font-family: 'Times New Roman',Times,serif;">[18] Tan W.K., Lin Q., Lim T.M., Kumar P. and Loh C.S. (2013). Dynamic secretion changes in the salt glands of the mangrove tree species //Avicennia officinalis// in response to a changing saline environment. Plant, Cell & Environment 36:1410–1422. <span style="font-family: 'Times New Roman',Times,serif;">[ <span style="font-family: 'Times New Roman',Times,serif;">19] International Union for Conservation of Nature (2014). Avicennia alba. Retrieved from: [|http://www.iucnredlist.org/details/178830/0](Accessed on 26th October 2014). <span style="font-family: 'Times New Roman',Times,serif;">[20] Schwarzbach A.E. and McDade L.A. (2002). Phylogenetic Relationships of the Mangrove Family Avicenniaceae based on chloroplast and nuclear ribosomal DNA sequences. Systematic Botany 27:84–98. <span style="font-family: 'Times New Roman',Times,serif;">[ <span style="font-family: 'Times New Roman',Times,serif;">21] Ghosh P., Das S. S. and Das S. (2014). [|Phylogenetic relationship among three species of the mangrove genus //Avincennia// found in Indian Sundarban, as revealed by RAPD analysis.]Asian Journal of Plant Science and Research 4:25-30. <span style="font-family: 'Times New Roman',Times,serif;">[22] Duke N.C., Benzie J.A.H., Goodall J. A. and Ballment E.R. (1998). Genetic structure and evolution of species in the mangrove genus //Avicennia// (Avicenniaceae) in the Indo-West pacific. Evolution 52: 1612–1626. <span style="font-family: 'Times New Roman',Times,serif; line-height: 1.5;">[ <span style="font-family: 'Times New Roman',Times,serif; line-height: 1.5;">23] Alongi D.M. (2002). [|Present state and future of the world’s mangrove forests]. Environmental Conservation 29:331–349. <span style="font-family: 'Times New Roman',Times,serif; line-height: 1.5;">[ <span style="font-family: 'Times New Roman',Times,serif; line-height: 1.5;">24] McKee K. L. (1996). Mangrove ecosystem: Definitions, distribution, zonation, forest structure, trophic structure, and ecological significance. In: Feller I. C. and Sitnik M. (eds). [|Mangrove ecology: a manual for a field course. A field manual focused on the. biocomplexity on mangrove ecosystems]. 1–6. <span style="font-family: 'Times New Roman',Times,serif;">[ <span style="font-family: 'Times New Roman',Times,serif;">25] Ewel K.C., Twilley R.R. and Ong J.E. (1998). [|Different kinds of mangrove forest provide different goods and services]. Global ecology and biogeography letters 7:83–94. <span style="font-family: 'Times New Roman',Times,serif;">[ <span style="font-family: 'Times New Roman',Times,serif;">26] Sulochanan B. (2013). [|Mangrove ecosystem and its impact on fisheries.] Central Marine Fisheries Research Institute. 57–62. <span style="font-family: 'Times New Roman',Times,serif;">[27] Robertson A. I. and Blaber S. J. M. (1992) [|Planktons, epibenthos and fish communities]. In: Robertson A. I., Alongi D. M. (Eds.), Tropical Mangrove Ecosystems. Coastal and Estuarine Studies No. 41, American geophysical union, Washington, DC (1992), pp. 173 – 224. <span style="font-family: 'Times New Roman',Times,serif;">[28] Macnae W. (1974). Mangrove forest and fisheries. FAO. Rome. IOFC/DEV/74/34, 35 pp. <span style="font-family: 'Times New Roman',Times,serif;">[ <span style="font-family: 'Times New Roman',Times,serif;">29] Roach J. (2004). [|Mangroves are nurseries for reef fish, study finds]. National Geographic news. <span style="font-family: 'Times New Roman',Times,serif;">[ <span style="font-family: 'Times New Roman',Times,serif;">30] Donato D. C., Kauffman B.J., Murdiyarso D., Kurnianto S., Stidham M., and Kanninen M. (2011). Mangroves among the most carbon-rich forests in the tropics. Nature Geoscience, 4: 293–297. <span style="font-family: 'Times New Roman',Times,serif;">[ <span style="font-family: 'Times New Roman',Times,serif;">31] McIvor A., Möller I., Spencer T., and Spalding M., (2012). [|Reduction of wind and swell waves by mangroves]. Natural Coastal Protection Series: Report 1: The Nature Conservancy and Wetlands International. <span style="font-family: 'Times New Roman',Times,serif;">[32] Sivakumar, A. and Kathiresan, K. (1990). Phylloplane fungi from mangroves. Indian Journal of Microbiology, 30(2) : 229 – 231. <span style="font-family: 'Times New Roman',Times,serif;">[33] Sivasothi M. (2003). Mandai mangrove and mudflat. Retrieved from: []. (Accessed on 20th October 2014). <span style="font-family: 'Times New Roman',Times,serif;">[34] Lee Kong Chian Natural History Museum (2014) Prawn farming. Retrieved from: [] (Accessed on 3rd November 2014). <span style="font-family: 'Times New Roman',Times,serif;">[35] Yim M.W. and Tam N.F. Y. (1999). Effects of wastewater-borne heavy metals on mangrove plants and soil microbial activities. Marine Pollution Bulletin 39:179–186. <span style="font-family: 'Times New Roman',Times,serif;">[36] van Maren D.S., Liew S.C. and Hasan G.M.J. (2014). The role of terrestrial sediments on turbidity near Singapore’s coral reefs. Continental Shelf Research 76:75–88. <span style="font-family: 'Times New Roman',Times,serif;">[37] Torio D.D. and Chmura G.L. (2013). [|Assessing coastal squeeze of tidal wetland]. Journal of Coastal Research 29:1049–1061. <span style="font-family: 'Times New Roman',Times,serif;">[ <span style="font-family: 'Times New Roman',Times,serif;">38] Purnobasuki H. (2013). [|Characteristics of root caps in four root types of //Avicennia marina// (Forsk.) Vierh.]American Journal of Plant Science 4: 853–858. <span style="font-family: 'Times New Roman',Times,serif;">[39] http://dictionary.reference.com/. Accessed on 23rd November 2014.