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Field notes from the Arctic Circle and Southern Siberia

LiveMint logoLiveMint 14-04-2017 Dhritiman Mukherjee

I have always been fascinated by the ice-covered areas of the temperate and Arctic regions. Recently, after I turned to documenting sub-aquatic flora and fauna, that fascination became a quest to study ice-covered aquatic ecosystems—frozen seas, lakes and rivers.

A Sea Angel, a type of hydrozoan, swims in the depths of the White Sea. Micro- organisms and dust particles present in the water appear in the background as stars in a moonless sky.

A Siberian sunset seen from the banks of Lake Baikal.

There are differences between lakes and seas, including size, currents and levels of salinity. For example, due to the salinity of sea water, the freezing point goes down to around minus 2 degrees Celsius, whereas freshwater lakes freeze at 0 degree Celsius. This has an impact on the way ice forms, the depths at which life is found, even the types of life that flourish here.

A distinct feature of the ice formation in the White Sea is the action of low and high tides on the pebbles present in the shallow water and on the rocky banks, close to the surface. Here, a comb jellyfish is seen under the ice surface.

Transparent ice formation in Lake Baikal.

When I decided to photograph the ice formations and life in the Arctic underwater, I included both sea and freshwater systems to understand the difference. For this I chose to work in Lake Baikal, in southern Siberia, and the White Sea, on the north-western coast of Russia (the White Sea is part of the Barents Sea, which in turn is part of the Arctic Ocean), in winter. Lake Baikal is the largest (by volume), deepest, oldest lake, one of the cleanest in the world, and has several unique features—it is, for one, a habitat for the endemic Nerpa seal, one of the very few freshwater seal species in the world.

More than 80% of the species found in Lake Baikal are endemic to the lake, including 350 species of amphipods. Here, a member of the ‘Acanthogammarus victorii’ family of amphipods walks past a sponge.

A gorgon’s head (centre) can be seen against coldwater soft coral growth on either side. This soft coral, ‘Gersemia fruticosa’, is endemic to the Polar and Arctic regions and is found at depths greater than 80ft. Because of this depth, the corals are able to survive even during the summer as temperatures remain at freezing point.

The White Sea has an opaque layer of ice, about a foot thick, whereas Lake Baikal has a much thicker transparent ice cover (80cm). As a result, there is greater penetration of light in Baikal. There was more plankton activity in both places than I had expected. During one dive in Lake Baikal, I found a bottom surface at a depth of 24m (78ft), and was able to observe sponges and amphipods. There were very few fish closer to the ice surface but the water was rich in phytoplankton.

Ice formation in Lake Baikal is distinct from the formations in the White Sea. The key dynamic influencing this activity is the temperature shifts during the day, which lead to the expansion and contraction of ice, causing collisions and cracks. The ice slabs can be as deep as 8m.

Kelp forests occur worldwide throughout temperate and Polar coastal oceans. They are recognized as one of the most productive and dynamic ecosystems on earth. A wide range of sea life uses kelp forests for protection or food, including fish, particularly rockfish, and many invertebrates such as amphipods, shrimp, marine snails, bristle worms and brittle stars. Here, we see a starfish lying on a kelp forest under the White Sea.

In the White Sea, on the other hand, life was abundant. I observed many sculpins. Shrimp, jellyfish, nudibranchs and hermit crabs could be seen in large numbers. On one deep dive, I found soft corals that are endemic to the Arctic water, as well as gorgonians. There was a good population of anemones. The ice formations, however, were more dramatic in Lake Baikal, with sizes reaching up to 5-6m, even up to 8m.

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