June 20, 2011
The oceanography watch has conducted 23 transects of 1-2 hours duration with the video plankton recorder (VPR). Three of these were tows across the shelf slope break. When the VPR is towed at a single depth to target a plankton layer, we’re studying plankton patchiness. If it’s towed across depths, that’s to get images of oceanographic transect and vertical plankton distributions.
We have done eight vertical CTDs (to 500m where possible!), and in conjunction with the day watch we have completed 21 standard bongo hauls and two special sample hauls targeting gelatinous zooplankton for researchers interested in sea turtle diet.
Offshore samples have been dominated by gelatinous zooplankton: the ctenophores Bolinopsis spp. and Pleurobrachia pileus in the north, and the salp Salpa democratica with smaller Pleurobrachia pileus and Beröe to the south. A couple of northern tows had layers of Euphausiids. Inshore samples consisted of smaller, more diverse zooplankton including copepods, Obelia spp. Hydromedusa, chaetognaths, and the pteropod Limacina spp.