IB Biology Ecology Fieldtrip

The Biology fieldtrip was an amazing and extremely fun experience which was organized at Pranburi, Thailand and allowed us to investigate different factors in the ecosystems: Mangrove forest and the man-made Rocky shore. The factors that were being observed included biotic such as amount of individuals of each species, competition within the ecosystem and water supply, and the abiotic factors included temperature, pH level, turbidity, other nutrients in the water (ammnia, phosphate, nitrate, oxygen) and etc. 

Mangrove

In the Mangrove forest, we were divided into two groups to go to two different sites (Site A and Site B).  Site A was located further away from the river where there were more mostly Red Mangroves which grow in soft mud in that area.  Red Mangroves are characterized by their prop roots which supply air to the underlying roots and provide support and stability to the red mangrove. In site A, we observed the light intensity of the water was quite low compared to the light intensity of water in site B since the water was cloudy and the sunlight was blocked by the leaves of the Mangrove trees.  Site B is located next to the river and further into the forest. Slightly different methods were use in the two sites to obtain the measurements since site A has water on its site, therefore, we can directly take the sample from the site and use different probes to measure the different factors. However, Site B consists of solid soil where we have to take sample of the soil and dissolve it in distilled water to gain most of the measurements except for water temperature and turbidity where we can measure it from the river next to the site using a thermometer and turbidity kit. The technique that was used in Site A was placing a quadrat by random sampling and the technique that was used in Site A was a transect line.

Figure 1: Comparing eight different abiotic factors in Site A and Site B of the Mangrove Forest

According to figure 1, it can be see that some of the other abiotic factors that were observed were air temperature, water temperature, dissolved oxygen in water, pH level of the water, turbidity and other nutrient concentrations in the water. We can see that there are no significant differences in the measurements of each abiotic factor for the two areas. The only two measurements that are different are air temperature and water temperature. The lower air temperature in Site A may result from the observation that was made earlier about the branches and leaves of the Mangrove trees that cover the place. This high density of mangrove population may block the amount of sun and wind penetrating through the forest, thus lowering the air temperature.  Since this reason cannot account for the higher water temperature in site A than in site B, other factors such as time of the day may have affected this. All these factors will affect the distribution of different species in the area which will be discussed further on the biotic factors.

The biotic factor that was investigated was the distribution of species in the two areas which can be seen in Figure 2.

Figure 2: Comparing the amount of individuals in each species in Site A to Site B 

We can see that there are not much significant differences in the amount of individuals of each species in the two sites except for the Red Mangrove and seeds where we can see slight differences. We can also observe that the Lichen green and Lichen yellow are very numerous compared to other species. The seeds are more commonly found in Site B which may be explained by the fact that these seeds need a more solid area to grow since unlike mangroves, they do not have air roots to allow them to live in the water. The Red Mangrove is more commonly found in Site A since they are more adapted to living in the damp area as opposed to the solid soil in site B. From this graph, we can estimate and conclude that the diversity in the two areas are relatively very close. This may be because even though they are located in different areas, they are still in the same ecosystem with very similar abiotic components. The water of the damp soil in Site A probably originates from the river next to Site B.

Rocky Shore

The Rocky shore we investigated was man-made where rock piles extend approximately 40 meters into the ocean. The method that was used in the rocky shore area was different from what we did in the Mangrove Site A since instead of using random sampling of quadrats, we used a transect line (As shown in the picture below). By using a transect line, we can observe the changes in the distribution of living organisms of different species from the rocks into higher depth of water. 

The abiotic factors that were being measured included temperature of water, wave frequency, wind direction, aspect and light intensity. Temperature of the water can be easily measure using a thermomter while the wave frequency can be obtained by the counting the number of waves that crashes into the shoreline per minute. The wind direction and light intensity are just direct observations. The aspect was obtained by calculating the slope of the angle of the rocky shoreline where we had to use a protactor to see that the line between two poles is around 90 degrees. The values of these measurements are shown in Figure 3.  

Figure 3: The measurement values for different abiotic factors on the rocky shore

Abiotic Factors	Measurement Values
Temperature of water	31.5 ºC
Wave Frequency	48 tides per minute
Wind direction	Northeast
Aspect	70ºNW
Light Intensity	Partially clouded

Acorn Barnacles

Other than these abiotic factors, we also investigated the biotic factors which are the different amount of species that live on the rocky shore. We had to count the amount of different species per quadrat along the transect line. The species that was the most abundant was the barnacles. Barnacles (right) are crustaceans that are recognized by their jointed legs and shells of connected overlapping plates. Unlike other organisms, instead of crawling after food, they attach themselves to rocks, ships or even whales and wait for food to wash by with the waves. When the waves wash over them or when the barnacles are submerged under water, they reach out their legs to filter out plankton and absorb oxygen. This is the reason why barnacles are the most abundant species on the Rocky shore.  This also explains the correlation between the amount of barnacles and depth of water (distribution of barnacles). More barnacles were counted in the quadrat where the barnacles are slightly submerged under water.

Knobbly Periwinkle Snails

This is because they will have constant food supply in the water and obtain oxygen at the same time. Another organism that was also abundant was the knobbly periwinkle snails(left).  It is believed that the shells of these snails help them withstand the high temperature. The other two organisms that were observed were rocky periwinkle snails and limpets. The distribution of some of these organisms is shown in Figure 4 which is a kite diagram of the abundance of species along the Rocky shoreline. We can see that the abundance of species changes as the depth of water is higher (Quadrat 1 low depth to Quadrat 9 high dept). For example the Acorn Barnacles with the most abundance in quadrat 7 where it is almost fully submerged and the abundace is rare for quadrats below quadrat 4 since these areas are the areas where the waves do not crash into as much. We can also observe that the amounts of rocky periwinkles is almost stable throughout the quadrats while the limpets are considered to be rare. 

Figure 4: The Abundance of Four different Organisms Along the Rocky Shoreline

There were several learning outcomes of going to this trip. Firstly was to learn how to do measurements of different factors that are essential in an ecosystem. Secondly, I believe this is a more direct way of learning how the distribution of certain organisms change according to competition with other organisms or the other abiotic factors. By 'direct' I mean we get to actually carry out experiments using quadrats and transect lines instead of just studying from the textbook and trying to grasp on the ideas. For example the barnacles that prefer to live nearer to the water or the Red Mangroves which would be abundant in damp areas. I also learned that there are many abiotic factors which can contribute to determining the characteristics of an ecosystem even though we had investigated only a few. The slightest changes in these factors may affect the organisms in that ecosystem. Lastly, another valuable thing that I learned was that biology trip is the one of the most awesome trip ever and starfish is the best team ! :) 

Starfish FTW :D