Monday, August 3, 2009
I had a blast yesterday, my advisor wasn't kidding when she told me how interesting and how much fun this class was suppose to be, according to students that took this class in past.
The weather started out sunnier and later in the day the clouds got a little heavier. During the ride in the first boat professor Bernan explained something which I never paid much attention to, natural selection. How new species are introduced to the Eco-system and how others succumb.
When we arrived at the Lovells Island we had a chance to hear a small introduction about the island by one of the park rangers. Looking at the map on the sign by the entrance I notice a small spot on the northern part of the island where we would end up walking by and learning about invasive plants as well and its impact on the salt marsh.
Our first stop was at Cobble Beach where we learn about the "Brazil nut phenomenon" where small particles like sand end up at the bottom and larger objects end up on top. Cobble Beach was a perfect example of that, we saw not much larger rocks at higher ground. We also talked about the effect of people, erosion and the periwinkles on the shape and size of islands.
Our first organism to be analyzed was the periwinkles, an introduced specie brought from Europe more than 100 years ago. We found many dead ones as well as some live ones. Professor Bernan mentioned that periwinkles can destroy or modify the size of sand area on beaches. We also learned about how they survive. Other than food moisture is very important for them. They have are covered with a protective operculum works as natural door that keeps the periwinkle from becoming dry, for instance low tides.
After having lunch with the "lunch less" members of the hockey team...we walked by the salt marsh. I apologize for not recalling the lady's name, we learned about the invasive species of plants, Fragmite weed, pepper weed-smells like horse hadish- which can adapt very well to salted water.
Arriving at the other side we were able to analyze the abundant life withing the tidal pool. We found more periwinkles as well as tunicates on the rocks and the invasive Asian shore crabs.
After leaving the tidal pool we went to a part of the island where they were many land snails, white-lipped snails and grove snails. Professor Benan asked us if the we anyone thought that these snails have anything to do with the periwinkles and some us said yes, they could be decedents of the periwinkles but further research would be necessary to affirm it. These land snails are very popular in Europe and are found in grassland areas and also wood areas. I understood that they love humidity.
What caused the holes on the periwinkles?
After some reading on the web I keep getting mixed information. Some sites did mentioned that blue crab as a predator but what it sounded more convincing to me was the moon snail. The moon snail is one of the top predators of the intertidal environment.
Where did the snails we saw at the beach come from?
The oyster-catcher is to blame. They use their bill to firmly hold the shell of the land-snail and with a lot of pressure it crushes the shell feeding on the snail. So I think as the during this process the bird could be flying therefore dropping the empty shell on other parts of the island.
What kind of crab were those at the tidal pool?
According to the the MIT website, they are an invasive species native from the western Pacific ocean was introduced to the southern New England shores more than a century ago.
What are the differences between the live and dead snail shells?
I thing the difference is mainly the exposure to the weather and where it occurred.
Re-do of the Barking Crab Journal
After reading the students' assignment#1 including my own I found out that what I though was sponges were indeed the invasive tunicate. In regards to my own comments about the Red-eye Amphipod, they could vary in size depending on the growth stage.
See you later,