Friday, August 6, 2010
Treasures of Spectacle Island - Some Observations and Research
At around 12.30 pm on August 4th 2010, we left for the Spectacle Island from Boston Harbor. The tide was low at about an average height of 4-4.5 ft. It took about 15 minutes to reach the island which used to be a big municipal landfill or a garbage dump about 300 years ago. After we landed on the docks, I noticed that the water clarity was about 7/10 and that the left side (where swimming was permitted) of the beach (from the docks) was all covered in sand, whereas on the right side there were a lot of rocks. It suggests that the sand on the left part of the beach was probably brought and dumped by humans in order to make it attractive to swimmers.
As a matter of fact, the entire island has been landscaped to accommodate visitors and it is hence, one of the most popular islands in the Boston Harbor and also one of the most important parts of the Boston Harbor National Park. However, there is no camping allowed on the island as in comparison to the Lovell's island. This is probably due to the risk of uncontrollable fires caused by the presence of methane gas under the ground which generates during the decomposition of the organic material.
Also, looking around the beach, I noticed that there were no sub-tidal shallow pools present on the beach as they were probably filled up by the garbage that was dumped on the island years ago and also maybe due to the human landscaping on the islands. This also suggests that the marine life found on the island would be similar as well as different in many ways to the marine life found on Lovell's island. As we walked down the rocky side of the beach, we were to look for any live welches or moon snails or even their big shells. Individually, we also looked for a thing that we thought was the coolest on the beach.
Alongside the discovery of the latter, we also took a hula hoop as group and placed it on 2 different parts of the beach. We examined the different common materials present in both the areas inside the hula hoop ring and made cylindrical-piled groups of the items. We measured the diameters and also the heights of the piles of the different items we had grouped in order to find th volume of each item present in the given ring area. This was and effort to find the relative abundance of the different items in terms of the space they occupied in any given area in separate parts of the beach. Of course, after finding the volumes, the density of the various items present in the ring area would give a more accurate relative abundance estimate. But, due to limitations on the instruments we carried with us to the beach, we could not possibly weigh the objects accurately and hence, could not calculate the density.
After having fun with the hula hoop experimenting for relative abundance on the beach as well as having a few who delightfully performed tricks with it, we gathered all the coolest things that people found on the beach and tried to identify some of them. We finished the group activities and then headed towards the docks for refreshments. Some people decided to go and have a swim into the sea while others like me filled up our starving bellies with some food from the Summer Shack. At around 4pm, after the fun day, we took a ferry on our way back to Boston with some of us (incl. me) in possession of the coolest things we found.
Hula-Hoop and Emily: (With Kind Permission - Hope you don't mind Emily!)
People found things ranging from the skeleton of dead sea animals, to the cover like flap that the moon snails have inside of their shells (which they use to hide and cover themselves up), to automotive and electrical parts, and also a lot of different kinds of sea glass. Some pictures include the following:
Individual Observations and Collections:
1) Moon Shells: Even though we were no able to locate up any moon snails, we did find a number of big broken moon shells on the beach, near the rocks. They were broken down on the rocks it seems and then the snails were eaten after the removal of their shells. Maybe, it was a thrush who did that but to me the thrushes seem to be too small to carry a huge moon snail. So it may have been something else.
2) Rock with a perfectly drilled hole: As a part of the activity to collect the coolest thing as per me on this island, I found a very smooth stone which was oval in shape and had a perfect hole through the upper middle part of it. The hole was small on one side and it was bigger on the other, suggesting that it had something like a nail, with a fat, long head pierced through it. I could not possibly think of something which may have such a structure other than for aesthetic reasons.
Relative Abundance Exercise:
As a group, we selected a spot that was very close to the wrack line. It was about 20 yards away from the sea water at around 1.15pm when the tide was moderately low still with an average of around 4.5-5 ft.
Spot 1 Area
The hula hoop had a diameter of around 30 ft (radius of 15 ft approx). Therefore, the area under examination was of about 700 square inches.
We sat around the hula hoop and made separate piles for the items present inside the area. We found small rocks, shells, sea glass, and ceramic/porcelain items mainly.
Small Rocks Shells
Sea Glass Porcelain/Ceramic
After assembling the items in a cylindrical manner, we measured the dimensions in order to get the relative abundance in cubic inches of each of the items present in the 700 square inch area of the beach near the wrack line.
1) Small Rocks: Diameter - 12 inches, Height - 1 inch. Volume = 113 cubic inches approx.
2) Shells: Diameter - 2 inches, Height - 0.5 inch. Volume = 6 cubic inches approx.
3) Sea Glass: Diameter - 6 inches, Height - 1 inch. Volume = 28 cubic inches approx.
4) Ceramic/Porcelain: Diameter - 3 inches, Height - 0.5 inch. Volume = 3.5 cubic inches approx.
Therefore, it is evident that the small rocks are in highly abundant in the wrack line area, followed by the sea glass, shells and then the ceramic items.
As a group we again selected the second spot. This was 2 yards away from the sea water at around 2pm, when the average tide was about 5 - 5.5 ft. We repeated the same procedure as in the spot 1 to get the relative abundance in cubic inches of the various items found in the area.
Spot 2 Area Large Rocks
Small Rocks Ceramic/Porcelain
Shells Sea Glass
The relative abundance in terms of volume for the different items was as follows:
1) Big Rocks: Diameter - 12 inches, Height - 3 inches. Volume = 339 cubic inches approx.
2) Small Rocks: Diameter - 10 inches, Height - 2 inches. Volume = 157 cubic inches approx.
3) Sea Glass: Diameter - 3 inches, Height - 0.5 inch. Volume = 3.5 cubic inches approx.
4) Ceramic/Porcelain: Diameter - 1 inch, Height - 0.25 inch. Volume = 0.20 cubic inches approx.
5) Shells: Diameter - 1 inch, Height - 0.25 inch. Volume = 0.20 cubic inches approx.
Therefore, the big rocks and the small rocks were relatively the most abundance items in the area near the sea, followed by sea glass, and then matched by ceramic as well as shells.
I was able to get a general idea of the relative abundance of different items and species in different parts of the beach (near the wrack line and at the shore). In conclusion, as we move up from the water level towards the wrack lines, the relative abundance of the rocks decline, and the relative abundance of all the other items increase. There may be more rocks near the water levels as due to higher presence of periwinkle snails that are proven to reduce sand levels on beaches. Also, the abundance of ceramic and sea glass probably increases as we move upwards as due to higher human activity in the areas and also the remains from moon tides.
Radius (r) = 0.5 * Diameter
Area = 3.1425 * r-squared
Volume of Cylinder = 3.1425 * r-squared * height