22 November 2004
|Jennifer here- well, today was another lovely day at New Harbor. The skies were blue and the weather was warm, so warm that the dry streambed that runs near camp actually had water flowing through it! Flowing water is not a normal sight down here.
We all dove at a hole that we had been melting for the past few days, "Side Show". To our surprise and joy, when Andrew and I jumped in first, we fit through the hole without a problem, which meant, bye bye to the Hotsy. So we packed up the 600 lb bucket of bolts and readied it to be sent back lovingly to McMurdo via helicopter. We held a party for its service and for the subsequent passing of the middle of the night fuelings. We also celebrated, because we all learned through Bob’s update from Nov 20 that Stacy and Bob are now engaged! We celebrated with a nice dinner and some silly dancing to Irish music. Congratulations Stacy and Bob!
|General life history schematic of a sea urchin, from: http://www.nhm.ac.uk/palaeontology/echinoids/INTRO/REPRODUC.HTM
||Now, I would like to take this time to tell you all about the project I am working on while down here on ‘The Ice’. As Stacy eluded to in her update yesterday, there are differences in the benthic community on either side of McMurdo Sound. Most of the species living in this community (e.g. seastars, sea urchins, worms that are conspicuous on the seafloor and worms that live in the mud, and snails) have a complex life history. This means that they do not give birth to young as we do, they either release gametes into the water column that collide to form embryos and subsequently larvae, or they brood embryos on their bodies that are released as larvae. The larval stage is pelagic (free swimming) and it allows the sedentary organisms to disperse their young and thus increase their genetic diversity. The larvae are in the water column from weeks to months until they settle, and metamorphose into benthic juveniles, resembling their parent.
One reason I really enjoy studying larvae is to see the varied forms of larvae that are strikingly different from their respective adults. This is similar to the radical metamorphosis from a caterpillar to a butterfly that you are probably all familiar with. See for yourself:
|To determine whether larval supply might be driving the differences in the benthic community on either side of McMurdo Sound, I am conducting plankton tows at different sites on either side to census what larvae are present. I am hoping that there will be a correlation between the types of larvae observed in the water column and the types of adults found on the seafloor.
|The brachiolaria larva of a seastar
||The veliger larva of a snail
| This will turn into a burrowing worm (polychaete)
| The pilidium of a Nemertean worm