The next day, after another intensely delectable meal of bacon (mmmmm),eggs, and other mouthwatering goodies, we loaded up the buses again and zoomed off to the mangrove forest!! There, we conducted investigations on the ecology of a mangrove forest and the rocky shore area of the nearby beach. The mangrove forest we visited was situated next to Pranburi River, while the rocky shore was a man-made structure protruding from the sandy shore into the ocean. The two aforementioned explorations will be the subject of the following two blogs:
Mangrove Investigation
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| Top: mangrove A Bottom: mangrove B |
At
the mangrove forest, we investigated two areas. One area was next to Pranburi
River, which will be referred to as mangrove B for the remainder of the blog, while
the other was further inland, and will be referred to as mangrove A. Mangrove B
was dominated by yellow mangroves, whereas mangrove A was dominated by grey and
red mangroves.
At each site, both abiotic and biotic factors were observed. With regards to abiotic factors, the temperature, dissolved oxygen, pH levels, salinity, water quality, turbidity, water depth, light intensity, and substrate were tested, and the results were recorded and compared.
In order to assess the biodiversity of each site, the Simpson’s Diversity Index was used, and the number of organisms present for each species observed was recorded. At mangrove A, the data collected was restricted to a single 1 meter by 1 meter quadrat, while at mangrove B, the data was collected using a perpendicular transect. Approximately 10 meters long and 1 meter wide, the transect ran perpendicular to Pranburi river.
At each site, both abiotic and biotic factors were observed. With regards to abiotic factors, the temperature, dissolved oxygen, pH levels, salinity, water quality, turbidity, water depth, light intensity, and substrate were tested, and the results were recorded and compared.
In order to assess the biodiversity of each site, the Simpson’s Diversity Index was used, and the number of organisms present for each species observed was recorded. At mangrove A, the data collected was restricted to a single 1 meter by 1 meter quadrat, while at mangrove B, the data was collected using a perpendicular transect. Approximately 10 meters long and 1 meter wide, the transect ran perpendicular to Pranburi river.
As it was the first time I had ever been in a mangrove
forest, everything I saw was new to me. The first lesson I learned was that mangrove
ecosystems have amazing biodiversity, and that, although it looks rather serene
from the point of view of someone standing on the boardwalk, the roots of the
mangroves house multifarious organisms. I also learnt that, while the mangroves
by the river were completely different in structure from those inland, they
were still all mangroves, but were just of different species. On a lighter yet more traumatic note, I also learned that red ants in mangrove forests are crazily sticky--once they cling onto your shirt, or even PAPER, you'll have a super difficult time getting them off--blowing is futile. Adaptation and natural selection, anyone?
After our investigations, we were further familiarized with the Pranburi mangroves as we compared the data from the two sites. Our large group was split into smaller groups, with a total of 12 people collecting data in my group (The Red Crabs). Once in that small group, we were split into 2 more groups (R-1 and R-2), so each group of 6 collected data on their own, resulting in two sets of data per site. The data from which we drew our conclusions is represented below.
After our investigations, we were further familiarized with the Pranburi mangroves as we compared the data from the two sites. Our large group was split into smaller groups, with a total of 12 people collecting data in my group (The Red Crabs). Once in that small group, we were split into 2 more groups (R-1 and R-2), so each group of 6 collected data on their own, resulting in two sets of data per site. The data from which we drew our conclusions is represented below.
Table 1: Abiotic Factors in Mangrove A
and B--reports the air and water temperature,
dissolved oxygen levels, pH levels, salinity, substrate descriptions, water
quality, turbidity, depth of water, and light intensity in both sites.
Table 2: Biotic Factors in Mangrove A
and B--reports the species present and the abundance
of each species in both sites. * The red and yellow coloring indicates the species
of mangrove present--red codes for red mangroves (specifically Rhizophora
mangle), while yellow codes for yellow mangroves (specifically Cerops
tagal).
Figure 1: Comparison of Species
Abundance in Mangrove A and B--graphically displays the numbers of each
species present at each site.
Using this data, we can calculate the biodiversity of
each site using the Simpson’s Diversity Index. This uses the formula: Diversity (D) = [N(N-1)]/∑[n(n-1)], where N is the total
number of organisms, and n is the number of organism of a particular species.
The higher the D value, the higher the diversity. Plugging in our values for
the abundance of species at each site, we get 3.88 for site A, and 1.56 for
site B, showing that there is a greater biodiversity inland than next to the
river.
From the above data, and the Simpson’s Diversity Index
calculations, we can conclude that the environment that the inland red mangrove
forest provides is more conducive to biodiversity than that which the riverside
yellow mangrove forest provides. What must be noted in looking at the results
is also that the yellow mangroves are much smaller species which do not sport
stilt roots, and thus live in dense clusters, while red mangroves do sport
stilt roots and thus cannot be that close together. This is the reason for the small
number of mangroves in the quadrat we observed at the inland site (mangrove A).
With regards to abiotic factors, site A (inland) had
higher air temperature and turbidity (the lower the turbidity the clearer the
water) than site B (riverside), as well as soil that was more moist and muddy,
rather than sandy, while site B had higher water temperature, dissolved oxygen,
pH, salinity, and nitrate and phosphate levels. The light intensity in both
areas was low, as there was thick foliage due to the tall mangroves. This makes
sense because it is near the river, which flows rather rapidly and therefore has
more dissolved oxygen, and there is a constant flow of nutrients which come with
the river’s current. Therefore, technically, mangrove site B should be more
conducive to the growth of organisms, as high dissolved oxygen and nutrient
levels means fertility and better living conditions for most organisms. It must
also be noted, however, that while mangrove A’s ground was submerged in water,
mangrove B was completely dry, with the exception of the river. This means that
the quality of the river water has little effect on the growth of the organisms
in mangrove B, as the mangrove forest was not in the river, but next to
it.
Additionally, it must also be noted that site A has many
organisms which are adapted to the environment already and can survive perfectly
well in the saline, submerged environment. This includes fish, crabs, and tapeworms,
all of which would not live amongst the mangroves in site B, but in the river,
and as such were not included in our observations. Therefore, I learned, from
this investigation, that despite the apparent serenity of the red mangrove
forest and the difficult conditions (what with all the water which went up and
down with the tides, which I figured would prevent fish and snails from
inhabiting the area), it is actually a diverse ecosystem because the organisms
living there are adapted for the environment already. Additionally, I learned
that the mangrove forests are protectors of the coast, slowing down waves, lessening
the impact of natural disasters such as tsunamis and hurricanes, and providing
a safe environment for the growth of organisms, so much so that it can be
called a nursery.
Rocky Shore Investigation:
After our tumble in the mangrove forest with malicious branches and super-sticky red ants, we had a charming lunch at a beach-side hotel. Lunch itself was awarding enough, but afterwards, we were given free time to frolic on the sandy shore, taking pictures and having a completely carefree break--something that is so hard to come by these days. Although I'm sure we all wanted it to last the rest of the day, we of course had to get back to the point of the field trip and continue our investigation at the nearby rocky shore, which turned out to be really fun anyways.
At the rocky shore, which was essentially a man-made platform extending into the ocean constructed out of rocks piled on top of each other, we used a perpendicular transect to see the abundance of various organisms as we went further into the ocean. As the rocky shoreline had a gentle slope as it went deeper into the ocean, we were able to calculate the slope by using the following set up:
The quadrats, which were 0.5 meters by 0.5 meters, were
placed adjacent to each other going from the lowest pole and away from the
ocean towards the highest pole. In each quadrat, the number of organisms was
counted and recorded. To determine the total distance between the poles, a tape
measure was used and the distance was measured perpendicular to the poles (along
the red line), which stood straight up. In addition to taking inventory of all
the organisms present along the continuous belt transect, we also measured the
abiotic factors, which included air and water temperature, wave frequency, wind
direction, aspect, and light intensity.
As was earlier mentioned, there were two sub-groups in our Red Crab group, and my group, R-1, went to the open-ocean side of the platform, while R-2 went to the beach-facing side of the platform. As the data for R-2 somehow disappeared, the following comparison will be using R-1's data collection for the open-ocean condition and the pink group's data collection for the beach-side condition. As the quadrats were numbered differently between our two groups, the table below might look flipped compared to the pink group's tables, it had to be reformatted so that each quadrat referred to the same thing.
Once we collected our materials, we waded into the water (which was hip-deep--which meant that I dunked my camera in the seawater several times--I'm sorry, camera!! >3<) and began our investigation!!
As was earlier mentioned, there were two sub-groups in our Red Crab group, and my group, R-1, went to the open-ocean side of the platform, while R-2 went to the beach-facing side of the platform. As the data for R-2 somehow disappeared, the following comparison will be using R-1's data collection for the open-ocean condition and the pink group's data collection for the beach-side condition. As the quadrats were numbered differently between our two groups, the table below might look flipped compared to the pink group's tables, it had to be reformatted so that each quadrat referred to the same thing.
Once we collected our materials, we waded into the water (which was hip-deep--which meant that I dunked my camera in the seawater several times--I'm sorry, camera!! >3<) and began our investigation!!
Table 3: Abiotic Factors at Rocky
Shoreline--indicates the air and water temperature,
wave frequency, wind direction, aspect, and light intensity at both the open-ocean and beach-side sites.
Table 4: Biotic Factors at Rocky Shoreline for Open-Ocean Site--indicates the abundance of each species according to quadrat.
Figure 2: Kite Diagram of Species Abundance at Open-Ocean Site--indicates the abundance of each species observed along the rocky shoreline for the open-ocean site, with quadrat 1 being furthest into the ocean, and quadrat 6 being almost completely out of the water.
Figure 3: Kite Diagram of Species Abundance at Beach-Side Site--indicates the abundance of each species observed along the rocky shoreline for the beach-side site, with quadrat 1 being furthest into the ocean, and quadrat 6 being almost completely out of the water.
As the first kite diagram above (Figure 2) shows, the abundance of rock periwinkles, acorn barnacles, limpets, and knobbed periwinkles increased as we went further from the ocean and up the rock shoreline. However, there appears to be an optimal location for these organisms, as there were 300 acorn barnacles in the 5th quadrat, and none in the 6th. The same goes for rock periwinkles, as there were 9 in the 3rd quadrat, 6 in the 4th, 5 in the 5th and none in the 6th. For limpets and knobbed periwinkles, we can assume that the optimal location is either further inland, as it is not contained in our transect area, or they simply were not abundant at the location which we were investigating.
The second kite diagram shows a slightly different distribution of organisms. The knobbed periwinkles are more widely distributed between the 6 quadrats, with the most at quadrat 5. On the other hand, rock periwinkles were only found in quadrat 6, compared to the wider distribution on the open-ocean side. Acorn barnacles, however, were most abundant in quadrat 5 in both conditions, although the number of acorn barnacles in the open-ocean condition was much higher (300 barnacles) compared to the number of acorn barnacles in the beach-side condition (7 barnacles). Lastly, limpets were apparently much more abundant on the beach-facing side of the platform, although the amounts on each side were difficult to compare accurately, as R-1 counted the number of limpets, while the pink group measured the abundance in percent.
As the first kite diagram above (Figure 2) shows, the abundance of rock periwinkles, acorn barnacles, limpets, and knobbed periwinkles increased as we went further from the ocean and up the rock shoreline. However, there appears to be an optimal location for these organisms, as there were 300 acorn barnacles in the 5th quadrat, and none in the 6th. The same goes for rock periwinkles, as there were 9 in the 3rd quadrat, 6 in the 4th, 5 in the 5th and none in the 6th. For limpets and knobbed periwinkles, we can assume that the optimal location is either further inland, as it is not contained in our transect area, or they simply were not abundant at the location which we were investigating.
The second kite diagram shows a slightly different distribution of organisms. The knobbed periwinkles are more widely distributed between the 6 quadrats, with the most at quadrat 5. On the other hand, rock periwinkles were only found in quadrat 6, compared to the wider distribution on the open-ocean side. Acorn barnacles, however, were most abundant in quadrat 5 in both conditions, although the number of acorn barnacles in the open-ocean condition was much higher (300 barnacles) compared to the number of acorn barnacles in the beach-side condition (7 barnacles). Lastly, limpets were apparently much more abundant on the beach-facing side of the platform, although the amounts on each side were difficult to compare accurately, as R-1 counted the number of limpets, while the pink group measured the abundance in percent.
From this
investigation, I learned that different organisms are adapted for different
environments. The difference in distribution of the organisms on either side of the platform would most likely be due to the different abiotic factors. One obvious difference was wave frequency--which was at 20 waves per minute on the open-ocean side, and 16 waves per minute on the beach-facing side. This might mean that certain organisms which aren't able to deal with the turbulent waters would have to occupy later quadrants which were further from the ocean, so that they wouldn't be hit with the full brunt of the waves and be washed off the rocks or killed. Of course, it’s not like this concept of adaptation affecting habitat hasn’t been taught to
biology students again and again, but to see it in nature so obviously like
this is still awesome.
In
conclusion, I learned a lot about ecology and how to use lots of different equipment
throughout the course of our biology field trip. But despite our busy schedule,
I had a lot of fun, cooperating with classmates while conducting our
investigations, enjoying group activities, and socializing during dinner. Every night my roommates and I
got back to our rooms absolutely exhausted and fell asleep as soon as our heads
hit the pillow, but it was definitely a trip I’ll always remember fondly!! The most memorable part might have been the present-giving on the last night--everybody's presents and speeches were just so touching and authentic or unique in some way that it was probably the best secret-Santa type activity I'd ever seen.
