Saturday, August 1, 2009

Assignment 2

Hi everyone! Hope you all enjoyed today's first class as much as i did. In going over my notes after wards, i noticed some similarities and some differences in the organisms i observed in the 3 main sites we visited: the Aquarium port area, the Rowes Wharf dock, and the Barking Crab dock. I would like to start by first talking about some species that i think are common to all three sites. The green leafy seaweed that was found in all 3 areas i believe is sea lettuce based on its color and leaf shape. The reddish/brown seaweed found on all areas that are constantly submerged, such as floating docks or shallow water below the low tide line, is possibly red fern or sea oak, based again on its color and leaf shape (though i am basing this observation on reasonably distant pictures). lastly, i think that the majority of mussels that were seen in all 3 sites were blue mussels. After taking one home and rinsing it off, i noticed that its black coating easily flaked off and underneath was a bright blue outer shell and a pale purple tinge on the inner shell, both characteristics pointed out in the guide book.

Characteristic of the Aquarium port only was rockweed, the darker brown bladder-algea clinging to the rocks near the sea wall. This was the only rocky/truely intertidal area we observed, which is why this species was only found in this site; it can survive being exposed when the water line receeds during low tide.

The mystery oragne-colored animal/mineral/vegitable that was first observed under the Rowes Wharf dock, then later again at the Barking Crab (cheetos) i believe to be red beard sponge. I am basing this identification on 2 main characteristics. First, the "mystery" orange thing seemed to come in a variety of shapes and sizes, ranging from the size of a dime to several inches in length. The smaller sized patches were most likely younger sponges that had not fully developed yet, and the larger and more complex areas older and therefore more developed. Second, i managed to pull some of this orange creature out from beneath the Barking Clam dock, and after it had been allowed to dry, it had clearly turned to a brownish color. This characteristic is mentioned specifically in the guide book. Also, to the touch it felt very soft and gooey, what i would have imagined a sponge to feel like.

The following animals were found at the Barking Clam site only. First, i think the barnacles that were seen there were ivory barnacles, based on slightly on their appearence, but mainly on the fact that they were found in brackish water conditions. Second, the i think the sea star we saw was a type of asteriid sea star, based only on its distant appearence. Third, after pulling out some mussels from under the dock, my group noticed that they were covered in there tiny shrimp-like creatures. We agreed that they might be either water fleas or fish lice, but are unsure since they were so tiny and therefore difficult to observe.

Lastly, the most vibrant creature we observed was what i believe to be a golden star tunicate, pictured at the top.

Looking at the picture taken from the Barking Crab last year, it seems as though there is more of everything we saw in general, but specifically larger mussels than any i saw today. I think the reason for this is that the water may be slightly fresher that it had been last year due to increased rainfall, and since mussels are capable of living in deeper areas of brackish water, i think they may respond to this change (since deeper water tends to be of a higher salinity in brackish conditions). Also, an increase in rainfall brings about in increase in nutrients, which would certainly cause the overall increase in abundance of all the organisms as observed.

See you all tomorrow!
Sam Gifford

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