Terry
November 12th, 2007, 10:21 AM
Diving Under the Polar Ice
A public lecture at the Canadian Museum of Nature
Dive into the underwater world of the polar seas in a lecture by marine biologist Dr. Kathleen Conlan on Wednesday, November 21 at 7:00 p.m. Conlan, who studies organisms living on the Arctic and Antarctic sea floors, will talk about how these animals thrive under the sea ice and how they adapt to changing conditions. Conlan, who has been a researcher with the Museum for 28 years, started working in the Arctic 17 years ago. She is an experienced polar sea diver and has photographed numerous wondrous benthic creatures (organisms that live on the sea floor) that are sheltered by the sea ice.
In her talk, Conlan will explain the benefits of sea ice. Organisms thrive in the water under the ice that is undisturbed by wave action. Sponges, for example, can grow up to an impressive two metres in height. And, very importantly, the ice provides insulation and reflects the sun?s radiation.
The ice can protect but it can also wipe out some sea life. Ice scours ? the scraping of the ragged bottom of moving ice along the coastal sea floor ? will destroy living things in its path.
?Weedier organisms replace the vulnerable ones but, surprisingly, the result is a mosaic of recolonizing fauna on the sea floor, resulting in an overall increase in diversity,? says Conlan. She studied the effects of ice scours on the sea floor in Canada?s Eastern Arctic at Resolute on CornwallisIsland from 1990-1999. From 2000 to the present, she has been working in the Western Arctic in the Beaufort Sea. Conlan is also looking at how the small marine invertebrates respond to the mud volcanoes from the natural gas percolating out of the sea floor at depths up to 70 metres. The murky water from the Mackenzie River means that the researchers collect samples from carving out cores of sea bottom instead of diving. Conlan also dives in the Antarctic, where she has worked on 11 field trips ? the last in 2004.
?For diving, it?s a lot better for us in the Antarctic because we?re under ice that?s attached to the land nearly year-round so the marine life is unique,? says Conlan. ?Deep sea animals (invertebrates such as sponges) can live much shallower because they are protected from storms by the stable ice.?
But the ice can pose some problems. A few years ago, a large chunk broke off the Ross Ice Shelf. ?It prevented the waves from the open ocean from breaking up the ice back to McMurdo Station where we work,? says Conlan. ?So instead of having the annual two metres of sea ice to dive through, it grew to six metres thick. That, along with a thick snow cover, made it nearly pitch-black underwater. We had to keep our cool and not foray far from our dive line. It also had a big impact on the penguin colony, which was reduced in size because the birds had longer to walk to the open water.? There are some differences between the oceans at the two poles. The Antarctic waters have been cold for 30 million years whereas the Arctic has been cold for only one million years. Shell organisms in the Antarctic, such as snails and clams, have thinner shells than their warmer water cousins and are therefore more vulnerable to the acidification of the ocean caused by greenhouse gases. And as there are no crabs in the Antarctic, which are predatory, this enables thin-shelled scallops and brittle stars to proliferate. Conlan?s slide and video show is part of a series of lectures in celebration of the International Polar Year. The IPY is the largest-ever international scientific research programme in the polar regions. Thousands of researchers from more than 60 nations around the globe are participating in the IPY, which continues until March 1, 2009. The lecture fee is only $5 and is free for CanadianMuseum of Nature members with individual memberships. To register for the lecture, call 613-566-4791. The Museum is located at 240 McLeod Street (at Metcalfe) in Ottawa.
A public lecture at the Canadian Museum of Nature
Dive into the underwater world of the polar seas in a lecture by marine biologist Dr. Kathleen Conlan on Wednesday, November 21 at 7:00 p.m. Conlan, who studies organisms living on the Arctic and Antarctic sea floors, will talk about how these animals thrive under the sea ice and how they adapt to changing conditions. Conlan, who has been a researcher with the Museum for 28 years, started working in the Arctic 17 years ago. She is an experienced polar sea diver and has photographed numerous wondrous benthic creatures (organisms that live on the sea floor) that are sheltered by the sea ice.
In her talk, Conlan will explain the benefits of sea ice. Organisms thrive in the water under the ice that is undisturbed by wave action. Sponges, for example, can grow up to an impressive two metres in height. And, very importantly, the ice provides insulation and reflects the sun?s radiation.
The ice can protect but it can also wipe out some sea life. Ice scours ? the scraping of the ragged bottom of moving ice along the coastal sea floor ? will destroy living things in its path.
?Weedier organisms replace the vulnerable ones but, surprisingly, the result is a mosaic of recolonizing fauna on the sea floor, resulting in an overall increase in diversity,? says Conlan. She studied the effects of ice scours on the sea floor in Canada?s Eastern Arctic at Resolute on CornwallisIsland from 1990-1999. From 2000 to the present, she has been working in the Western Arctic in the Beaufort Sea. Conlan is also looking at how the small marine invertebrates respond to the mud volcanoes from the natural gas percolating out of the sea floor at depths up to 70 metres. The murky water from the Mackenzie River means that the researchers collect samples from carving out cores of sea bottom instead of diving. Conlan also dives in the Antarctic, where she has worked on 11 field trips ? the last in 2004.
?For diving, it?s a lot better for us in the Antarctic because we?re under ice that?s attached to the land nearly year-round so the marine life is unique,? says Conlan. ?Deep sea animals (invertebrates such as sponges) can live much shallower because they are protected from storms by the stable ice.?
But the ice can pose some problems. A few years ago, a large chunk broke off the Ross Ice Shelf. ?It prevented the waves from the open ocean from breaking up the ice back to McMurdo Station where we work,? says Conlan. ?So instead of having the annual two metres of sea ice to dive through, it grew to six metres thick. That, along with a thick snow cover, made it nearly pitch-black underwater. We had to keep our cool and not foray far from our dive line. It also had a big impact on the penguin colony, which was reduced in size because the birds had longer to walk to the open water.? There are some differences between the oceans at the two poles. The Antarctic waters have been cold for 30 million years whereas the Arctic has been cold for only one million years. Shell organisms in the Antarctic, such as snails and clams, have thinner shells than their warmer water cousins and are therefore more vulnerable to the acidification of the ocean caused by greenhouse gases. And as there are no crabs in the Antarctic, which are predatory, this enables thin-shelled scallops and brittle stars to proliferate. Conlan?s slide and video show is part of a series of lectures in celebration of the International Polar Year. The IPY is the largest-ever international scientific research programme in the polar regions. Thousands of researchers from more than 60 nations around the globe are participating in the IPY, which continues until March 1, 2009. The lecture fee is only $5 and is free for CanadianMuseum of Nature members with individual memberships. To register for the lecture, call 613-566-4791. The Museum is located at 240 McLeod Street (at Metcalfe) in Ottawa.