Monday, August 3, 2009

Location: Lovells Island

Date: August 2, 2009

Conditions: 75º F, cloudy and breezy, tide lowering

Beach (west side of the island)

Observations: On the cobble beach, we learned and observed first hand the “Brazil Nut” phenomenon; where the larger rocks lay atop the smaller ones. Also discussed was the subject of intertidal and shallow-water snails consuming the algae, which would have held the sand in place on the beach. Some hollow snails were found to have holes in there shells. I've found the exact origin of this cause to be somewhat conflicting. I was not able to find evidence of the crabs or moon snails being the preditors, nor was I able to conclusively say that Nucella lapillus (L.) was the cause; even after reading a case-study done, since their main prey are barnacles and mussels. Finally, the theory I have to answer the question of the reasons there are snail populations both on shore and on trees on the land with different colors is due to evolution. How did they get there, I suspect that strong wind and surf from storms carried these original shoreline snails inland, causing them to adversely adjust to their new habitat. Since I've already burned many hours trying to find a reliable source to help explain this, I'll try again later.

Beach (east side of the island)

Observations: After lunch, we crossed over the old, dried up marsh and continued on to the other side of the island. There we turned over rocks where I found a gulfweed crab. In addition, hermit crabs were also moving around in the shallow water.


Observations: Inland, we observed Cepaea hortensis in trees and on leaves. We also learned the preferred diet of these snail is calcium.

Beach (east side of the island - low tide)

Observations: Finally, we concluded our observations with the tide out. We lifted rocks and found lobsters hiding and running quickly when discovered in shallow water. In addition, large underwater rocks when brought to the surface revealed sea squirts (as demonstrated by Alexandria), red beard sponge, and various bushy bryozoans .

Attached are also some interesting related articles I found while doing my research.

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