Sunday, April 17, 2011

Narwhals and Their Melting World

Last week’s news reports note that scientists now predict that the Arctic will be ice-free in summer as early as 2016.  While that may be somewhat welcome news to shipping companies seeking a more reliable route through the Northwest Passage or for oil exploration companies anticipating a longer working season, or even for those southern Greenlanders looking for a longer growing season, it is not good news for many Arctic marine mammals that depend on that ice as a feeding or resting platform or for a reliable place to find food.  And that certainly includes narwhals.
             A recent research study concluded that narwhals and polar bears are the Arctic species at greatest risk from a warming climate.  While the polar bear situation has been told many times, few reports have described how narwhals will be affected.  Kristin Laidre, a narwhal researcher at the University of Washington, told me that the impact of climate change on narwhals may come from a wide range of factors.  
View from Qaanaaq, Greenland, Aug. 2010

“These include not only sea ice loss, but also changes in ocean regimes, such as altered ocean temperatures, salinity or currents that may change distribution of prey,” she said.  “There are also human impacts.  There is considerable interest in oil exploration and drilling in the Arctic as the region warms and sea ice disappears.  This comes with increased shipping, for example, through the Northwest Passage, as well as other activities that could potentially disrupt migratory routes and feeding areas, such as competition from developing fisheries, noise and pollution…If you’re a species that relies on specific predictable prey resources and you go exactly where they are found, then if something happens and the system changes you have to be able to adapt your behavior.  To some extent, these indirect impacts may make narwhals more vulnerable than the direct impacts of sea ice loss.”
It’s the narwhal’s inflexibility that seems to make it more vulnerable to changes in its marine environment.  They have very specific habitat and dietary needs, and warming waters may move their preferred foods north and away from their preferred habitat.  The northward expansion of southern species of whales, especially killer whales (a main predator on narwhals), could end up increasing competition for food and alter predator-prey relationships.  It could also make them more vulnerable to disease, especially new diseases that may expand their range into the Arctic. The melting ice has also triggered plankton blooms, which provide the basis of the food web, to occur 50 days earlier than they did just 15 years ago.  And that could mean that food availability during important times of year will shift, with uncertain affects on narwhals and other whales.
So while narwhal populations are presently somewhat healthy, the warming climate makes their future precarious.

1 comment:

  1. there are 60,000 narwhals in the world

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