We visited the Sungei Buloh Wetland Reserve on 5 June 2007. It was a one-day "IT Geographic Techniques" fieldwork cum research on the mangrove forests. It was quite tiring but we learnt alot of things and saw rare plant and animal species. Overall, I would say that we had a great time there!
We get to admire the scenery which cannot be seen in our daily lives such as the river and various trees with unique root systems. In addition, we get to see the mangrove trees during low and high tides. Furthermore, we get the opportunity to interact with the "wildlife" experiences. We get to taste the "Avicennia" leaves which are salty as they tend to secrete salt onto the leaves’ surfaces in order to regulate the amount of salt in it. In my opinion, it was a meaningful and interesting excursion for us as we get to learn a lot of things and have fun at the same time.
A mangrove is a tropical maritime tree or shrub of the genus Rhizophora. Mangroves have special aerial roots and salt-filtering tap roots that enable them to thrive in brackish water (brackish water is salty, but not as salty as sea water).
There are several species of mangrove trees found all over the world. Some prefer more salinity, while others like to be very close to a large fresh water source (such as a river). Some prefer areas that are sheltered from waves. Some species have their roots covered with sea water every day during high tide. Others are more sensitive to salinity, and grow closer to the shore. Other species grow on dry land, but are still part of the ecosystem.
Mangroves need to keep their trunks and leaves above the water line. Yet, they also need to be firmly attached to the ground so that they are not moved by the waves. There are three types of mangrove roots that help in this process: 1. Support roots which directly pierce the soil.
2. Level-growing roots which twist upward and downwards, with the upward twists emerging on the water surface.
3. Level-growing roots whose downward twists (sub-roots) appear on the water surface. Any part of a root that appears above the water line channels oxygen to the plant below the water line. Over time as soil begins to build up, these roots produce additional roots that become embedded in the soil.
Firstly, the mangrove forest consists of many species of plants that may benefit us in many ways. During the Asian tsunami in 2004, it was discovered that many lives were saved on low-lying islands with mangrove ecosystems intact. Hence, we need to preserve these environmental resources which may protect us us against the fury of Nature.
Secondly, protecting this natural heritage of Singapore also means protecting our only means of directly knowing more about Singapore’s history. Here, we get to see the former glory of the lush and green island teeming with light-footed squirrels, foraging monitor lizards and migratory snow white egrets, a rare sight now in an increasingly urban Singapore.
Thirdly, the mangrove forest is also one of the last frontiers of natural ecosystems found in Singapore. Here, amidst the lush greenery and tranquil surroundings, one gets to be at peace with oneself and with Nature. Take a deep breathe of fresh air and you can feel refreshed once again. It's not artificial but something REAL and COOL and definitely something which is vastly different from the simulated, cool air-conditioners in our classrooms.
At the bridge spanning across Sungei Buloh Besar, we felt like budding "environmental scientists" on a mission to find out about the possibility of eutrophication taking place along the river.
First, we scooped up water samples from the river with a bucket attached to a rope. Then using our PDAs and different sensors, we collected data on the pH values, dissolved oxgen content, nitrates concentration, velocity flow and turbidity.
Data Collected from Data Logger
(1) pH Value: 7.31 Time: 2.45
(2) Dissolved Oxygen Value: 5.21mg/L Time: 2.46
(3) Turbidity Value 63.30NTU Time: 2.47
(4) Current Flow Meter Value
(a) Left Bank of River: 0.00 m/s Time:12.02
(b) Middle Bank of River: 0.39 m/s Time:12.03
(c) Right Bank of River: 0.26 m/s Time:12.07
(d) Nitrates ISE Value: 14000.00mg Time:12.09
(e) Dissolved oxygen in water: Data not available at time of blogging
Dissolved Oxygen
It refers to the concentration of oxygen dissolved in the water. Factors affecting the concentration of dissolved oxygen include aquatic organisms dissolved oxygen from the water surface, build-up of organic wastes, temperatures, pressures and salinity.
Turbidity
Turbidity is a measure of the degree to which the water looses its transparency due to the presence of suspended particulates. Factors affecting turbidity include phytoplankton, sediments from erosion, resuspended sediments from the bottom, algal growth and waste discharge.
Current flow of water
A current, in a river or stream, is the flow of water is influenced by gravity. Factors affecting water current: stream gradient flow volume of water and channel geometrics.
Nitrate Ions in river
Factors affecting amount of nitrate ions: surface runoff by other areas. Nitrates and nitrides in fertilizers or waste products from nearby industries.
There is a higher turbidity reading of 63.30. We also observed that the river water sample is more cloudy compared to clear tap water. One possible reason could be the effects of the high tides that were present on 5 June around 12 noon.
We have no conclusive evidence from other readings that eutrophication takes place. Even though there are some prawn farms nearby, we are unable to get evidence of discharge of effluents.
However, there was other findings when we use the velocity flow metre sensor. The middle part of the river has a high velocity of 0.39 m/s compared to its left (0.00 m/s) and right (0.26 m/s) banks. This suggests that the river flow is faster in the middle of the river compared to the friction it faces at either sides. The flow at the left bank is stagnant and we did observe that there were leaf debris and traces of oil on the water.
Tides are the cyclic rising and falling of Earth's ocean surface caused by the tidal forces of the Moon and the Sun acting on the oceans. Tides cause changes in the depth of the marine and estuarine water bodies and produce oscillating currents known as tidal streams, making prediction of tides important for coastal navigation. The strip of seashore that is submerged at high tide and exposed at low tide, the intertidal zone, is an important ecological product of ocean tides. The changing tides produced at a given location is the result of the changing positions of the Moon and Sun relative to the Earth coupled with the effects of the Earth'a rotation and the local bathymetry. Sea levels measured by coastal tide gauges may also be strongly affected by the wind. More generally, tidal phenomena can occur in other systems besides the ocean, whenever a gravitational field that varies in time and space is present
What affects tides?
Tides are caused by the gravitational attraction of the sun and moon upon the earth's oceans, combined with the daily rotation of the earth. The motion of the sun, moon, and earth are entirely predictable, and so we can predict tides well in the future. Unfortunately, a large number of factors make the prediction process quite complex. As we demand more and more accuracy in the times and heights of our predictions, and therefore the process becomes more complex. For any given place, factors that affect tide heights and times include the location of the place on the globe, the depth of the sea, the shape of the coastline, the presence of rivers, bays and inlets, and other nearby land masses. Tides are also affected by non-predictable factors such as wind and the barometric pressure.
When do high and low tides occur?
In the morning to about noon is low tide which is from 8 in the morning to 12 at noon. As for high tide, it occurs from noon to afternoon which is from 12 o'clock to 3 o'clock.
Wednesday, August 1, 2007
