CONTENTS
Flora index
Fauna index
guide to the mangroves of singapore
The Ecosystem: Abiotic components
Peter K L Ng and N Sivasothi (editors)
 
Tides

In Singapore, high waters (HW; high, rising or flood tides) alternate twice a day with low waters (LW; low, receding or ebb tides). Caused by the gravitational pull and centrifugal forces of the rotation of the earth, moon and sun, tides are also modified by the local geography. 		Mangrove Ecosystem
Abiotic components
Soil
pH
Oxygen
Nutrients
Winds and currents
Light, temperature, humidity
Tides
Salinity

Biotic components
Vegetation
Zonation

Singapore experiences predominantly mixed semi-diurnal tides, i.e. the two high tides (and low tides) of a day are not of equal height (for a chart of this). Tide times shift by an additional 50 minutes a day since they are based on a lunar day, which is 24 hours 50 minutes long.

When the moon and sun align during a full or new moon every two weeks, the resultant spring tides (usually experienced two days later) are a high water spring tide (HWST) and a low water spring tide (LWST). The average between the two may be considered the tidal range, and in Singapore reaches a maximal of about 3.5 m. There are beaches in other countries with a tidal range of 10 m!
view of high water tide flooding a park trail
A rare HHWST will flood
even normally dry trails at
Sungei Buloh Nature Park

The area on a seashore lying between the highest high water spring tide (HHWST) and the lowest low water spring tide (LLWST) is the intertidal zone. The level exactly in between the two extreme tides can be taken to be the mid- tide level (MTL), and mangrove forests grow between MTL and HHWST (for a diagram of this).

Spring tides occur every two weeks, and between that period, the sun and moon approach at right angles to each other. Their gravitational effects are partially cancelled out and produce alternating neap tides, resulting in high water neap tides (HWNT) and low water neap tides (LWNT). When the moon is in its first and third quarter, the lowest tidal range is reached, and may shrink to as little as 0.6 m. Tidal behaviour varies with location and time, so consult a tide-table or the newspaper before you visit a mangrove anywhere. Some tidal prediction reources are available on the internet, click this link to see.
What is mangrove?
Introduction

The Ecosystem
Abiotic
Biotic

Value
Intro
Products
Indirect uses
Potential uses

About Mangroves
in Singapore
History
Mangroves to visit
Conservation
 
From "A Guide to Mangroves of Singapore", Peter K. L. Ng and N. Sivasothi (editors)
Volume 1: The Ecosystem and Plant Diversity and Volume 2: Animal Diversity
Authors: Kelvin K. P. Lim, Dennis H. Murphy, T. Morgany, N. Sivasothi, Peter K. L. Ng,
B. C. Soong, Hugh T. W. Tan, K. S. Tan & T. K. Tan
BP Guide to Nature Series published by the Singapore Science Centre, sponsored by British Petroleum
© 2001 Raffles Museum of Biodiversity Research, The National University of Singapore & The Singapore Science Centre