Glaciers calving icebergs into Hughes Bays. Large volumes of meltwater and sediments are carried into the bay with these icebergs, causing massive burial disturbance at the seafloor.
At the end of our stay in Hughes Bay, we went ashore in rubber zodiac boats to collect kelp (for food-web analyses) and to do a bit of site seeing. We encountered icebergs seeming designed by Gaudi, gentoo penguins and a large leopard seal dozing on an ice flow .
Gentoo penguins on the shoreline of Hughes Bay.
A large leopard seal lazily eyeing us from its napping spot on an ice floe. I think we look like lunch!
On the night of Feb 18, we transited south to Andvord Bay, the fjord just south of Cape Renaud (see map). There, we completed the earlier work within initiated in this fascinating fjord, using megacore and Blake trawl samples to document the remarkably rich fauna in the fjord basins. The trawl brought up huge numbers of giant polychaete worms. These worms are four inches long, one inch in diameter and stuffed to the bursting point with eggs and sperm. The biomass and diversity of these large worms in Andvord Bay are truly remarkable, indicating the seafloor at 500 m depths in the fjord is receiving much more food than the open continental shelf at similar depths. Most of the seafloor animals we re covered were filled with reproductive products and appeared ready to spawn, suggesting this has been a summer of high productivity. It appears that the fjords like Andvord Bay, because of their food-rich conditions, could be providing larvae to seed seafloor populations far beyond the fjord bounds. Because fjord conditions are being altered by climate warming (i.e., by increasing glacier melting and glacial sediment loading), the Andvord seafloor ecosystems are likely to be very climate sensitive, and may be transitioning to the depauperate conditions we observed in Hughes Bay. Clearly, the Antarctic Peninsula fjord communities merit much further to study to elucidate their patterns of causes of high biodiversity, and the sensitivity of these unusually rich communities to climate warming.
Sausage sized (4-inch long) polychaete worm from the floor of Andvord Bay. This ampharetid worm is white because it is bulging with sperm ready to be released into the water column during mass spawning.
Our final day in Andvord Bay was punctuated by a helicopter ride for the benthic ecologists (Laura, Craig and David). We flew from the ship to the desolate top of the Antarctic Peninsula, getting a view of the massive ice fields straddling the Peninsula. As we descended down a glacier back to the ship, the views were astounding, leaving impressions of stark beauty that we will retain for a life time.
The ice sheet atop the Antarctic Peninsula. This sheet extends unbroken for 1000 miles along the Peninsula to the main part of the Antarctic Continent.
View from the Helicopter as we fly down from the top of the Antarctic Peninsula into Andvord Bay.
On 24 Feb we completed our seafloor ecosystem studies along the west Antarctic Peninsula by deploying another whale bone lander south of Anvers Island, and then conducting an ROV dive in the Palmer Deep, a 1440 m deep basin off the southeast tip of Anvers Island. To our surprise, we found a large number of king crabs in the basin at depths below 1000 m, indicating that these invasive marauders have already penetrated deep onto the Antarctic shelf. As mentioned earlier, king crabs have been excluded from Antarctic ecosystems for possibly millions of years due to very low water temperatures on the Antarctic shelf. Climate warming in this region apparently is allowing these species to move shallower, threatening the vulnerable unique Antarctic seafloor communities. Where we found abundant crabs on the Palmer deep floor, we only found sea anemonies, suggesting that the brittle stars and crinoids had been consumed by the voracious, skeleton crushing crabs. This discovery of crabs in the Palmer deep is a sobering reminder of the vulnerability of Antarctic marine ecosystems to climate change.
Marauding king crabs marching across the floor of the Palmer Deep. These crabs are bad news for the endemic Antarctic benthic fauna!
After spending 25 Feb packing and stowing gear in the hold and on the upper decks of the NP Palmer, we are now heading north across the Drake Passage towards Punta Arenas (to be reached in four days time). The forecasts are for rough weather in the Drake -- nothing unusual in this part of the ocean! Our last views of the ice bound continent and islands were of Smith Island in the Bransfield Strait in the wee hours of the 26th. While we are all eager to get home after two long months at sea, we will miss the scenery and ecosystems of Antarctica!
Antarctica tour is such a good traveling experience for any people. The mount climbing and wildlife of Antarctica is very unique and amazing.
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