Wednesday, August 6, 2008

Intertidal Pool, Lovell's Island

We started our field trip by taking a ferry from the Long Wharf Marina to Lovells Island. Our main objective was to explore the biodiversity of the intertidal pool areas. Professor Berman’s obsession with snails would lead our class to conduct another investigation into the variation of snails on the island. We arrived at Lovells Island at approximately 10:30 and moved to the north of the island. Once I arrived at our area of exploration I decided that it would be appropriate to record some basic data. I noted that the tide was relatively low, according to the tide charts indicated that low tide was forecasted for 07:57 and high tide for 14:14. The weather conditions were very pleasant and the estimated temperature was 78 degrees Fahrenheit. I observed that the beach consisted of a mixture of mud/sand, small pebbled rocks, and larger cobbled rock. The cobbled rock extended from the shoreline deep into the sea. The shoreline not only consisted of pebbled rocks but also a variation of sea-weed. There was evidence of Rockweed (Fucus sp.), Sea Lettuce (Ulve Lactuca), and Brown Algae more commonly known as Knotted Wrack (Ascophyllum Nodosum) or Irish Moss (Chondrus Crispus). The Sea Lettuce could easily be identified as it resembles lettuce and the Knotted Wrack had washed up on the shoreline. My cross examination using Google images could not confirm the different sea-weed that I witnessed, however pg. 54 of the Boston Harbor Seaside Educator’s Guide give’s added insight into the possible variations of seaweed on the New England Shoreline.

My tools consisted of a notebook, a pen, my blackberry, my eyes, and the instruction of Professor Berman. Our examination of the inter tidal zone began at about 11:15. The water temperature, at my estimation was about 15 degrees Celsius, but that may be considerably generous. I decided to taste the water to confirm that it was indeed salt water. My investigation of the inter tidal pool was rather brief because I could not bear to observe what was beneath me; however I was intrigued by the large presence of periwinkles. Professor Berman based our discussions and focused our attentions to the significance of the periwinkles. I observed common periwinkles (Littorina Littorea). Their size varied and ranged between a quarter or possibly half an inch to maybe two inches long. Their weight ranged between half a gram and three grams. The periwinkles were found attached to most of the cobbled rock. Most outer shell colouring was dark brown to black. Professor Berman dug up some tiny redish coloured worms that I was unable to accurately record and identify. I also caught sight of a few black crabs and my classmates managed to capture several Hermet Crabs (Pagurus sp).

After our midday break our class explored the vegetated area of Lovells Island in search of land snails. Our primary objective was to collect both live and dead snails so that we could attempt to identify possible variations or similarities between snails. Professor Berman indicated that snails preferred flat or low lying areas as opposed to hills or highly elevated areas. Thus my group descended into a low lying woodland brushy vegetated area in search of land snails. The majority of the dead and empty snail shells were found at the border between the road and the trees. The snails that were alive could be found tucked vertically hidden beneath the branches of trees and plants. My group gathered snails of different sizes and colours, which we then contributed to the class’s collection of snails. Our class gathered one hundred shells; we grouped the snails based on shell colour and stripes. The colour groups varied between yellowish/white, pinkish red, dark brown, white/brown striped, pinkish/brown, and yellow with one black stripe. Our class discussion proved inconclusive because we failed to find any significant differences between the snails apart from the colour of their shells. Although they might have varied in size and colour I felt that they were one common species of snail. After further research I managed to identify the snails as possibly Grove snails (Cepae Nemoralis) because according to Wikipedia the grove snail is very similar to the white-lipped snail (Cepaea Hortensis); they both live in the same environment and they are known to be highly ‘polymorphic’ – variation in colour and bandwith.

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