Sure, icebergs are beautiful. (See the photos I posted last summer, http://www.theearthconnection.org/blog/?p=83 ). And, as it turns out, icebergs are not just massive, barren formations; they actually support a great deal of life.

Indeed, observers have long noticed that icebergs–massive ice chunks that have broken off from glaciers– attract seals, penguins, and seabirds, according to Jeff Rubin, writing in Audubon (January-February 2009). Rubin, who has written about Antarctic icebergs for more than 20 years, also notes that fish are more numerous around icebergs than in the surrounding seas.

Scientists have learned in the last few years that icebergs also sustain a wide variety of tiny and–to us–strange little animals, including many that are translucent. (I wonder what life-serving advantage accounts for so many of these creatures’ translucence.)

Life in and around icebergs ranges from photosynthetic microalgae to six-foot tall sea sponges, according to David N. Thomas, author of Frozen Oceans: The Floating World of Pack Ice. Recent research has even revealed red algae growing on rocks embedded in the underwater portion of icebergs.

Iceberg fauna is not even limited to icy surfaces and surrounding waters. Researchers recently found a hidden garden of invertebrates living on the seafloor near an iceberg. Starfish, sponges, feather-duster worms, sea cucumbers, and other filter-feeding organsms take advantage of the iceberg’s tunnels and caverns, which channel currents of seawater full of plankton (food) to these waiting animals, reports Rubin.

Researchers have also seen juvenile fish living in finger-sized holes in icebergs. It is unclear whether these fish simply found and occupied the holes or whether they dug them out to escape from predators.

So what is it about icebergs that makes them such magnets for life, despite the bitterly cold environment? To find the answer, scientists looked far back in time. Back when today’s icebergs were part of even huger glaciers, these glaciers scraped across the land, accumulating ground rock and debris as they went. When calving (the process by which an iceberg breaks off from a glacier), the gradually melting iceberg slowly releases the debris, pulverized rock, and thousands of years’ worth of dust. This mixture acts as an oceanic fertilizer, adding to the ocean a variety of nutrients phytoplankton need to thrive. And phytoplankton are food for many, many of the animals living around icebergs.

In addition to supporting phytoplankton populations, icebergs, when grounded, provide shelter for bottom-dwelling creatures, which could otherwise be crushed by other free-floating icebergs.

Because phytoplankton growth removes carbon dioxide from the atmosphere, icebergs may play an important role in regulating climate change. Scientists are researching how much carbon makes its way into deep water.

Below are photos of animals who live in and around Antarctic icebergs. The first is a hydromedusa. The second is krill.–April Moore

This entry was posted on Sunday, January 18th, 2009 at 6:29 pm and is filed under Insights and Visions on the State of the Earth. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.