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>Seas: ca 1-2 feet
>Winds 20 knots
>Temp -1.5 C ; w/ wind chill –17.5 C
>Location: Latitude 63 degrees 42 42’ S; Longitude 57 degrees 22.00 W

Above and below: Icebergs are plentiful near the ship. Click on images for larger views.

A large seastar was the Catch of the Day. Click on image for larger view.

3 December 2004

Yet another day surrounded by glaciers, icebergs, and sheer cliffs. Today has been incredibly busy. We collect and processed two benthic samples (6 hours each) and then collected and examined a plankton sample. Both benthic samples were taken in areas characterized by soft, silty sediment. As one might expect, the majority of animals were either infaunal (living within the sediment) or were suspension-feeding organisms that stayed above the sediment by clinging onto other animals. Many of the annelid worms (segmented worms related to the common earthworm) that we collected live within tubes of their own creation. Given that the anus is terminal in these worms, what problems may be evident in the tube dwellers? How might this challenge be "solved?"

The spring bloom of phytoplankton in the Antarctic Peninsula is very evident. Most of the plankton tows we take (using a 202 _m mesh net) are colored brownish-green owing to the tremendous abundance of diatoms. Diatoms are photosynthetic protists that occur as single cells or occur as chains. Each individual is housed within two overlapping silicon dioxide dishes called frustules (visualize a Petri dish). As a consequence of their abundance, sorting plankton can be a very labor- and time-intensive endeavor, but their presence is indicative of the biological richness of these waters. They serve as important food items for primary consumers and represent a significant primary producer in this oceanic ecosystem.

I mentioned the problem of moving across a moving current (i.e., Antarctic Circumpolar Current, ACC). Well, there seems (to my mind) to be one primary means by which larval forms can traverse the ACC. If larvae are being dispersed across the Drake Passage, then "warm core" and "cold core" rings that form on either side of the Passage and the subsequent movement of these parcels of water may be the vehicle for larval transport. Next time you visit a stream, look for the formation of rings as a simple example of these oceanographic features. Gotta go.

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