Ocean's 4: Laboratory Report

LABORATORY REPORT:

EFFECTS OF THE DROWNING BOAT AND THE FLOATING BUILDING ON THE OXYGEN LEVEL OF THE OCEAN WATER AROUND THEM

INTRODUCTION: Stagnant water bodies have low dissolved oxygen levels. This is because as there is almost no wave action on the surface of such water bodies, the effectiveness of incorporating oxygen into it is very low. Also the process of decomposition uses oxygen thereby reducing the amount of dissolved oxygen if the ecosystem is not in equilibrium for this used oxygen to be replenished through the process of photosynthesis. With the floating building (docks) and the sinking boat not being parts of the natural environment of the ocean, it may have an effect on the dissolved oxygen level in the ocean water around it. Dissolved oxygen in the ocean is very important for the survival of the marine ecosystem as it is used by all organisms there-in the process of photosynthesis. For this experiment, we shall measure the dissolved oxygen levels in the ocean around the floating building, the sinking boat, by the docks and the rocky shore.

HYPOTHESIS: The amount of dissolved oxygen in the ocean surrounding the floating building and the sinking boat will be lower as compared to that in the middle of the ocean. The sinking boat and the floating building leave the surface of the surrounding ocean stagnant. Moreover, due to possible decomposition that may be going on under these structures, it is expected that the dissolved oxygen levels will decrease.

METHOD:

Collect samples from the various sites: floating building (docks), rocky shore, by the sinking boat and the middle of the ocean (about 10cm away from the structures).

Bottles filled to capacity under the surface of the water, tightly capped, kept under fairly a constant condition which can be likened to that in the ocean.

Prepare and calibrate the Oxygen Probe:

· Using a pipette fill the membrane cap with 1ml of Dissolved Oxygen Electrode Filling Soultion

· Place the Probe into a beaker filled with about 100ml of distilled water.

· Connect the Dissolved Oxygen Probe(DOP) to the interface

· Leave the DOP in the water and the connected to the interface with the data collection program running for 10 minutes. This warms up the Probe. The probe must connected at all times to keep it warm.

With the aid of the dissolved Oxygen Probe, measure and record the level of dissolved oxygen in each sample as follows:

· Place the tip of the probe into the water being tested (submerged 4-6cm). Do not deeply submerge

· Gently stir the probe in water sample. Monitor the dissolved oxygen concentration in the live read outs

(Collect and record data within 45 minutes of sample collection).

DEPENDANT VARIABLES:

· All samples were collected at the same time

· The same amount of samples were collected from each site

· Water samples were collected from approximately the same depth

INDEPENDANT VARIABLES:

· The temperature of the water at the various sites

· Surrounding air pressure as well as water pressure

RESULTS:

TABLE OF VALUES

Shore	Boat	Middle	Docks
9.7	9.9	9.7	9.6

Graph of Oxygen levels in the water samples from the different sites:

CONCLUSION:

From the results and the graph, it can be deduced that, the oxygen level is least around the docks, the highest amount measured around the boat. The possible reasons for this result are:

· There is more photosynthetic activity going on around the boat. This is evident as there was a great population of moss growing around the boat which obviously photosynthesises to release oxygen. The opposite may be the attributing reason for which the docks record the least amount of dissolved oxygen.

· It may also be concluded that there is a great population of organisms making use of oxygen as compared to the amount oxygen produced by photosynthetic plants around the docks. The opposite may be said to for the ecosystem around the boat

Even though the variation of the dissolved oxygen levels recorded was not that big, it is of great significance as the samples were taken under the same relative conditions.

Research:

Different levels of dissolved gases in seawater can tell us a lot about the ecosystems and organisms living in the water. Dissolved oxygen in the water is used to breathe, grow and live by sea animals with gills, bacteria, and other marine organisms. The cells of many various organisms rely on oxygen to survive. The oxygen levels are renewed through photosynthesis, carried out by marine plants, such as phytoplankton, seaweed and a variety of algae, and by diffusion. On sunny days, or in areas with few plants, dissolved oxygen levels can climb fairly high.

In terms of depth, the surface of the ocean water, (approximately the first 10 to 50 m) will have high levels of dissolved oxygen because of the ability of plants to go through photosynthesis so close to the surface and the sunlight. When these waters become saltier, they become heavier and therefore denser, and the molecules sink deeper in the ocean. This allows for diffusion throughout various depths.

Therefore, water towards the surface, with access to sunlight, will have higher dissolved oxygen concentrations. The water at very deep levels will also have high concentrations because there are not many organisms consuming the oxygen at those levels. The lowest amount of dissolved oxygen will actually be found at mid-depths, about 200 to 2,000 m from the surface.

If nutrients are dumped into seawater from waste areas, it can lead to an influx in the development of phytoplankton, eventually leading to a cycle that can reduce the oxygen levels from the water, perhaps consequently killing fish and allowing the production of hydrogen sulfide gas (H ₂S), which is toxic to many organisms.

By introducing a new object to Pedder Bay, such as the grounded sailboat, it actually creates a new eco-system. The plants and bacteria around this new ecosystem will require various amounts of oxygen, thereby changing the levels of dissolved oxygen in the bay close to said object.

dissolved oxygen graph.jpg

Oxygen levels (µMol/kg) vs. Depth (m)

Pacific Ocean north of Oahu, Hawaii

In terms of oxygen levels in seawater, versus freshwater, usually the salinity of water directly affects the dissolved oxygen levels. Therefore by increasing the salinity, the amount of oxygen available for organisms decreases.

FINAL THOUGTS:

The introduction of alien structures unto the ocean leads to a new ecosystem evolving which with time regains the equilibrium that the initial introduction may distort.

EVALUATION:

For more accuracy, measurements should have been taken directly from the various sites.

SAFETY PRECAUTIONS:

Safety precautions are very important in the process of scientific experimentation. Throughout this experiment, this fact was taken into great consideration, for example:

· Life jackets were worn on the boat trip to collect the samples

· A shore master was on the look for the safety of all boat passengers.

· The instruction manual of the Dissolved Oxygen Probe was thoroughly followed.

References and Bibliography:

Academic support:

- Judy, Biology teacher, group supervisor

- Catrin, Biology and Chemistry teacher

- Jonathan, lab technician

Websites:

http://www.waterencyclopedia.com/Re-St/Sea-Water-Gases-in.html

http://www.marinebio.net/marinescience/02ocean/swcomposition.htm

http://www.racerocks.com