Skinny Whales and Global Warming

Even if our own species does not go extinct in the near future, a sad consequence of global warming may be watching our neighbors on this planet die away.

Ice algae and ice bacteria are the seasonal food for both krill larvae and adults: the base of the food chain. It significantly contributes to the annual bloom of life in the cold polar and sub-polar waters and may be the primary reason polar seas are so abundant in life. The spring rain of this nutritional matter to the sea floor may also contribute to the quantity and health of floor dwelling (benthic) crustaceans; the food of gray whales.

The impact and appreciation of ice algae is a relatively new science spearheaded by Lisa Clough of Eastern Carolina University, and is still being quantified. One thing has become apparent though, ice algae is a “higher” quality food source than phytoplankton and is not replaceable on a one to one scale. Furthermore, while most phytoplankton remain dormant in dark winter months, ice algae can uniquely extract energy and multiply in brine channels in sea ice. This allows polar krill species to feed year round and maintain significant populations not to mention the spring break-up fertilization of the sea floor
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Krill, too, are affected by water temperatures. A massive coccolithophore bloom in the Bering Sea in 1998 resulted in a substantive decline in krill populations. Krill could not feed on the diminutive phytoplankton. Krill are not the direct food source for gray whales as they are for other baleen whales but presumably the benthic crustaceans which feed the grays have a similar relation to ice algae. Krill may be a signal but the Northern Gray whale is probably a threshold species.

Recently, it has been noted that the Northern Gray whale population is suffering a drastic weight loss with the accompanying reproductive difficulties, morbidity and mortality. The populations suffering weight-loss may be diseased or may be stressed by other environmental factors, but, one possible hypothesis is that there simply isn’t enough food for them. As ocean temperatures rise there is less and thinner ice and a shorter “winter” as well, resulting in appreciably less ice algae, especially in the shallow Bering and Chukchi seas, where new data shows 20% reduction in sea ice in just the past few years. Seasonal sea ice in the deeper Arctic Ocean is becoming more common and ice algae may be forming in quantity there, but, this does not mitigate the gray whales problem as both the gray’s primary food and the gray’s ability to harvest seem limited to a depth of less than 300 feet.

An additional problem may include the increased distance of migration. The gray whale is already considered to have the longest migration of any mammalian species at about 22,000 km adding another 2000 km might simply be a sea too far.