December 22, 2016
We got an early wakeup call via a broadcast on the ship’s PA system from Expedition Leader Sue Perin, notifying us of a pod of humpback whales immediately off the bow of the ship! Everyone stormed up to the bow and bridge as quickly as possible, and we all met with sleepy eyes and bed head. Overnight, Captain Kruess had navigated us across the Bransfield Strait, down the Gerlache Strait, and into the Errera Channel. We were now very close to the western edge of the Antarctic Peninsula. This was an incredibly scenic area, and these early morning humpbacks represented our best looks so far this trip!
Our destination this morning was Danco Island, located in the southern end of the Errera Channel. We arrived, and I was able to hop on the first Zodiac for a ride around the island with naturalist Pete Puleston. Given Pete’s wealth of experience in the Antarctic, this was an incredibly informative adventure. The most memorable part of this excursion was the ice. Strewn throughout the channel were some of the most amazing ice formations that I have ever seen. Many, in fact, looked as though they had been purposefully carved in an aesthetic fashion, with brilliant striations, patterning, and even caves. And they weren’t solely white; quite a few were almost entirely blue!
What accounts for this color variance is the amount of air bubbles contained within the ice. When an ice formation is littered with air bubbles, the complete visible spectrum of light is scattered at the ice/air boundary (in the locations of the bubbles) and reflected back to the viewer. Accordingly, this ice appears white. However, when ice is free of air bubbles (more consolidated), light can penetrate the ice without being scattered. This ice appears blue for the same reason that large quantities of water appear blue. As light travels through the ice, the portion toward the red end of the spectrum is preferentially absorbed; the further this light travels through the ice, the greater the extent of this absorption. Accordingly, the deeper the slab of bubble-free ice, the bluer the ice (Carleton University). Specifically, it is an overtone of the O-H bond stretch that is doing the absorbing (Braun and Smirnov, 1993); so this is the same in principle as IR spectroscopy (bond vibrations absorbing energy), except it concerns an overtone that absorbs in the visible spectrum (more energetic light). Very cool stuff!
On many of these slabs of ice, we encountered our second species of seal for the trip, the Crabeater Seal. Despite its name, this seal primarily feeds on krill and doesn’t partake of crab, whatsoever. I also got a first look at the Antarctic Shag, the Antarctic relative of the Imperial Shags I saw back in the Beagle Channel.
Pete eventually took us to Danco Island, itself. On the island, there was a man-made trail that traveled up to a great 360° viewpoint around 1000 ft. above sea level. Also on top of the hill was a large Gentoo penguin nesting colony. This was such a great spot, and I spent around 45 minutes looking around the vast southern end of the Errera Channel and observing the penguins going about their day-to-day lives. It was almost entirely quiet, the silence only occasionally broken by the harsh vocalizations of the penguins.
I observed a couple of very unique aspects of penguin behavior here. First, I observed a male penguin clearly stealing stones from the nests of neighboring penguins and using them to fortify his own nest (upon which his mate was lying). He continually did this for over 30 minutes, and his pilfering clearly irritated the penguins in the vicinity. According to naturalist Doug Gualtieri, this practice is common amongst brush-tail penguins (Pycoscelis), especially Gentoos. Brush-tail penguins build their nests out of small stones as a means of protection from flooding (ice-melt) during warm spells (National Wildlife Federation, 2005). A nest built on stones is more elevated and thus better protected. Each male builds a nest with the hope of attracting a mate, and females evaluate the quality of the nest in selecting their mates. This explains the stone-stealing.
Another interesting observation I made concerned the amazing network of “penguin highways” throughout the island. Penguins defecate frequently, and this excrement absorbs more energy from the sun than the surrounding snow. Over time, this has led to preferential snow and ice melt in areas where penguins commonly walk. As it is easier for penguins to traverse across these areas where snow/ice is melted and more compacted, there was a developed network of penguin trails on Danco Island connecting the colonies with each other and the ocean. Watching the penguins travel around on these highways was mesmerizing; each penguin had his/her own agenda and was using the most efficient road route to achieve it. It was very difficult not to anthropomorphize.
Back on the ship, we spent the remainder of the day exploring the Gerlache Strait and Wilhelmina Bay to the northeast of Danco Island. During a brief stop by Enterprise Island in Foyn Harbor, we encountered the wreckage of the Governoren, a whaling ship from 1915 which met its fate in a whale oil fire. Today, the only occupants of the ship are Antarctic Terns, which I observed diving for fish off of the rusted bow.
I am currently looking at a great sunset over the bay through the porthole in my cabin. It never gets dark here – sunset confusingly turns directly into sunrise. It doesn’t feel as though the day has ended, but I am ready to rest. We aren’t traveling much tonight, as we are planning to investigate the ice in Wilhelmina Bay a bit more tomorrow.
Grosvenor Teacher Fellow
National Geographic Society