Aquatic Field Studies – Agam's Blog

Over the last few weeks in Science 9 Honors, our class has been studying the four spheres; the biosphere, the atmosphere, the hydrosphere, and the geosphere. In association with the sphere’s unit, we have studied the biosphere and hydrosphere in our own backyard; the pond behind our school called the Oxbow Pond, and the mid-reach section of the Coquitlam River that is a few minute’s walk from our school. We studied the biotic and abiotic factors that contribute to the biomes of the pond and the river such as the nutrient measurements in the water using a water quality index and the living things that live in these habitats.

The Coquitlam River Study

We began our field study with the Coquitlam River. Over two field study sessions in our specific study area, we collected the data following data, in which we used tests such as a thermometer, a TDS meter, as well as data previously collected by a professional field scientist:

92% saturation of Total Dissolved Solids
0 pH units
1°C of temperature change between two opposite sides of our study area.
0 ppm of nitrates
4 mg of phosphates
2 NTU (turbidity)
50 mg Total Dissolved Salts

Calculating these measurements, we approximated that the water quality index of the Coquitlam River is 85, meaning that the water quality is good.

A good water quality score invariably reflects what we discovered at our Coquitlam River study site: water quality rarely exceeds norms, and if it does, it does so by a small margin. The water quality is good for most organisms, and there is a lot of variety in it. The river is also suitable for all sorts of recreation, including direct contact, according to the water quality score, which happens often in the summer when people go swimming and tubing all along the mid-reach.

Next, we created a tally of all the invertebrates and living things that we found in our study areas. Here we used the Surber Sampling technique when we had two people from every group of eight or so people stand facing downstream to collect any material and organisms living in the river with a net. By holding a stone in front of the net and scrubbing, we made loose invertebrates that were on the rock get pushed by the current into the net. Once the two people in waders finished and were ashore, we transferred whatever was caught in the net into a bucket of clean water by swiveling and shaking the net.

Here are the invertebrates and other living things that we found in our study site of the Coquitlam River:

8 mayflies
6 stoneflies
1 caddisfly
1 riffle beetle
1 dragonfly nymph

*We found no other living things in the river

This group of invertebrates that we sampled indicates that indeed, the water quality is good. We know this because riffle beetles, caddisflies, stoneflies, and mayflies are all Category One invertebrates, meaning they are sensitive to pollution in the water, while the dragonfly larvae are prone to almost any quality of water.

The Oxbow Pond Study

During our study of the Oxbow Pond as a part of this aquatic field study, we measured the water quality as we did for the Coquitlam River. Using the same methods and tests that we used to collect the nutrient measurements in the Coquitlam River study, we had the following data:

90% saturation of Total Dissolved Solids
5 pH units
5°C of temperature difference from two opposite sides of the site
20 ppm (nitrates)
5 mg of phosphates
8 NTU (turbidity)
100 mg Total Dissolved Salts

Calculating the measurements above, we approximated that the water quality index of the Oxbow Pond is 72, meaning the water quality is “good”. The term “good quality water” implies that the water quality has little deficiency and that life in the is very diverse.

The Process of Measuring Nitrate Levels

As in the Coquitlam River’s sampling, we had around 7 or 8 students put on waders and lifevests to go into the pond, although this time we did not use the Surber Sampling technique but rather just put the nets in the water in order to not get the grime from the bottom of the river mixed in with the organisms that we wanted to sample.

Here are the invertebrates that we found in the Oxbow Pond:

7 fish
3 gilled snails
1 scud
1 water mite
9 water boatmen
1 caddisfly
3 tadpoles
2 damselfly larvae
1 dragonfly nymph
2 mayflies
1 water snipe larvae
1 riffle beetle

The other living things found in the Oxbow Pond

1 lady Bug adult
1 chipmunk
2 stick bugs
3 snails
1 dragonfly adult
3 bugs on the surface

Using the information we have about the ideal habitat for invertebrates which we found in the pond, it makes perfect sense that category one invertebrates such as the riffle beetles, caddisflies, and mayflies were found as they are very sensitive to pollution, while other category two invertebrates such as scuds and damselflies were found in the water as they are tolerant organisms that are found in both good and fair quality water.

The Comparision

The two sites which we studied had things in common and yet even more indifference:

Both had relatively close measurements of Total Dissolved Solids.
Both had very similar temperatures 15°C and 16°C.
Both had relatively close measurements of phosphates
Both had Category 1 invertebrates such as the mayflies and caddisflies found.

The river had half the amount of Total Dissolved Salts as the pond.
The pond had double the amount of turbidity as the river.
The pond had 5 pH units while the river had zero
The pond had more than triple the amount of types of invertebrates and other living things than the river.
The pond had a different bottom than the river, which was mud, aquatic plants, and fallen trees, while the river had cobble and pebbles.
The pond had a very distinct, sewage smell while at the river all you could smell was the forest.
The pond had a mix of grasses, trees, and berry bushes around it, while the river mainly had trees and ferns on its bank.

I think that the main cause for the difference between the river and the pond has to do with the type of body of water they are; The pond is a body of small and murky water that is only refilled by the rain as most ponds are. The river is a vast part of a watershed that spans over kilometers and kilometers that flows rapidly starting all the way up the mountain. The river has different visual, abiotic, biotic, and even sensory components because of its long and comparatively old body, whereas the pond is shallow, has no flow, and I assume, was is either man-made or recently created naturally.

My Reflection

Overall, I really liked our aquatic field study. I think it helped me gain a better understanding of how a biome actually functions, and it really gave me a good perspective of what an actual field scientist would have to do. I loved doing the work outside, especially finding the critters. From doing this field study I learned so many new skills; identifying different types of invertebrates, distinguishing certain critters to be affiliated with certain water qualities, using actual water testing techniques, and learning how to calculate a water quality index.

I wouldn’t make any changes to the way we did these activities other than perhaps creating a better system to pass information when students were placed in larger groups because there were a few mistakes that were made in the process of collecting the samples.

This was such a fun experience that I really liked doing because it created a great bonding with whoever I worked with as we got to work and problem solve as a team. Thanks, Ms. Yorke!