Featured Image Credit: wildlifeobservationsworldwide.com
By Eva Gruber
Climate change is affecting the planet in a multitude of ways – many of which our scientists could even predict. One of those has been the change of ecosystem assemblages around the world as the abiotic factors (including climate) change. The change in weather and climate patterns spur a massive shift in the distribution and abundance of species. While most species suffer from the rapidity of the change, unable to evolve adaptations at such an unnatural pace, others are able to take advantage of the changes.
One such example is the expansion of orca whales further and further north. As ocean and air temperatures rise, and as the summer season becomes longer at the poles, sea ice cover is decreasing at an astonishing rate. Where sea ice has covered thousands of acres of Arctic Ocean during the long winter months, it has retreated far past historical points with the rise in temperature.
This has opened up habitat for species normally limited by ice cover, such as orca whales. Normally not found much further north past Alaska and the Aleutian Islands, orca whales have in the past few years been spotted as far north as Hudson Bay, in Manitoba, Canada.
This signifies a major shift in the food web dynamics in the ecology of the region. Where polar bears used to be the apex predator, orca whales – nicknamed the “wolves of the sea” – may now succeed.
Steve Ferguson is a marine scientists with Fisheries and Oceans Canada and the University of Manitoba, and will be meeting with other marine scientists this week to present his findings concerning orca whale expansion into the Arctic.
Historically, sea ice had physically prevented orca whales from traveling north due to the size of their dorsal fins. Arctic whales such as belugas and narwhals have tiny dorsal fins, which is an adaptation to navigating through ice covering the surface of the ocean. As the animals must breach through holes in the ice (polynyas) to grab a breath of air, a tall dorsal fin would get in the way and possibly prevent the animal from breathing.
Free from the restriction of sea ice, orca whales are taking advantage of the newly open waters and hunting new prey such as belugas and their young.
Despite a range expansion and possibly an initial increase in population, this is not good news for the overall health of the ocean’s ecosystems and the planet as a whole. While this may benefit orcas in the short term, it essentially represents the same ecological problem as invasive/introduced species, where novel species appear in a habitat completely unprepared ecologically and cause a multitude of trophic disturbances.
Ferguson says the predictions for ice-free summers are becoming earlier and more frequent. While there is still sea ice left in the Arctic, northern species still have some habitat and refuge left. But with the rate of melting, predictions are dire even two decades into the future.