SITES

	Greatham, Teesside, UK
	West Site, Billingham, UK
	Grimsby, Humberside, UK
	Calais, France
	Huelva, Spain
	Scarlino, Italy
	Teluk Kalung, Malaysia
Habitats on the Teluk Kalung Site Forests at Tiger Bay Mangrove Swamps Invertebrates Fish Amphibians and Reptiles Birds Mammals Biodiversity Management
	Umbogintwini, South Africa
	Lake Charles, USA
	Burnie, Tasmania

Index by Category

Appendices

References

Teluk Kalung, Malaysia

Mangrove Swamps

The terms 'mangrove' and 'mangrove swamp' are well understood but are difficult to define precisely and scientifically. Mangroves comprise of plants belonging to many different families and genera. What they have in common is the ability to grow in a rather difficult and relatively unstable environment. Typically, they are littoral plants of sheltered tropical and sub-tropical coastlines extending to about 25° north and south of the equator. In these regions, mangrove swamps usually occur when the following general characteristic conditions predominate:-

• Average temperature for the coldest month is 20°C or above and the seasonal range does not exceed 10°C.
• Substrate is mainly mud or muddy soil. However, some growth can take place on sand, peat or coral.
• There are protected coastlines since wave action prevents the establishment of mangrove seedlings.
• Saline water - there is some evidence to suggest that most species are not obligate halophytes, but most show optimum growth in the presence of some sodium chloride.
• A wide tidal range; the greater the range the more area that is available for mangrove communities.
• Favourable ocean currents to disperse and distribute seeds along the coast.
• Shallow shores since seedlings cannot become anchored in deep water
  (Walsh 1974).

Salinity
Salinity is an important factor in mangrove ecology. Although many species are not totally dependent halophytes some degree of salinity is required for optimum growth. Mangroves are essentially slow growing plants and cannot compete with faster growing more vigorous species. Most plant species are very intolerant of saline conditions. Therefore, the real importance of salt in mangrove ecosystems is that it keeps large areas free of vegetation and allows for colonisation by the slow growing but salt tolerant mangroves. The degree of salt tolerance of many species is not clear. Some, such as Acicennia marina have been found to grow over the widest range of salinity with a maximum tolerance of about 85%⁰ (more than twice the salinity of seawater). However, optimum growth takes place in water of between 8-15%⁰ with a soil range of 24-34%⁰. A general and detailed discussion of mangrove ecology is given by Tomlinson (1986) and a more popular account of world-wide mangrove forests and their associated flora and fauna by (Stafford-Deitsch 1996).

Ecological and Economic Importance of Mangroves
Like all wetlands, the mangrove forest ecosystems are of major ecological and economic importance:

• They act as a cleansing system, recycling nutrients and organic matter brought down by rivers and streams.
• They provide feeding and breeding grounds for many fish and crustaceans.
• They are a feeding, breeding and roosting habitat for a number of important bird species.
• They stabilise the land and help to prevent coastal erosion.
• They provide fodder for domestic animals.
• They are sources of firewood.

Threats to Mangroves
There are various threats to mangrove swamps. These include losses due to development, changing ecological conditions e.g. salinity, over exploitation of biological resources and pollution.

Pollution
There are two major factors that make mangroves particularly susceptible to certain types of pollution:
(i) they grow in metabolically stressful conditions and further stresses through pollution can prove fatal (ii) their modified root systems make them especially vulnerable to clogging.

Little work appears to have been done on specific pollution problems of mangroves in Malaysia but, in Florida, petroleum products have been shown to be a serious threat, causing severe metabolic alterations when absorbed. Whilst highly susceptible to herbicide run-off, mangroves in the southern USA do not appear to be adversely affected by highly eutrophic waters. They have, however, been killed by high loads of suspended fines and flocculent material (Myers & Ewel 1991). Tioxide have recognised the economic and ecological importance of mangrove habitats consequently none of the developments on the Tioxide site has involved direct damage to mangrove habitat and no site effluent streams are discharged directly into the mangrove ecosystem.

Mangrove Forests in the Vicinity of the Tioxide Plant
As in other parts of the world mangrove swamps are confined to muddy shores, lagoons and tidal estuaries and are mainly found along the sheltered west coast of Peninsula Malaysia. On the east coast distribution of mangroves is patchy around the mouths of rivers (Cranbrook 1986).

In the state of Terengganu on the east coast there are at least 14 mangrove areas associated with various river estuaries. Those found in the Chukai / Kemaman river system adjacent to the Tioxide site being the most extensive (Tioxide EIA).
The Sungei Chukai has mixed mangrove swamps at its mouth that include Rhizophora apiculata, Sonneratia alba and Brunguiera pavriflora. Further up-stream R. apiculata is still present together with R. mucronata and the palm Nipa fructicans becomes more abundant. Mangrove swamp on the Sungei Kemaman is less extensive, however, R. apicualta, R. mucronata, Ceriops decaridra, Xylocarpus granatum and Bruguiera gymorhiza are all found.

Ecological Importance of the Chukai / Kemaman Mangrove Swamps
As discussed above mangroves re-cycle nutrients and the Chukai / Kemaman Estuary has some of the highest concentrations of phytoplankton on the east coast of Peninsula Malaysia. This has been attributed to the high nutrient levels provided by the mangrove swamps (Chua 1984). This abundant plankton nourishes the food chain in the estuarine and coastal waters.

Some species such as the prawn Machrobrachium rosenbergii, the Mangrove Crab (Scylla serrata) and various species of fish are of commercial importance, but many more species support the wetland food chain. Considerable numbers of birds are found in the mangrove swamps, these include Green Heron, Eastern Reef Heron and Mangrove Kingfisher that are particularly associated with this habitat. Other species such as Brahiminy Kite, White-bellied Sea Eagle and Southern Pied Hornbill are regular visitors from other habitats. A more detailed discussion of the birds on and round the Tioxide site is given in Section Birds.