The Nature of Fear

The thing I hate about horror movies is the silent moment before something jumps out to scare you. The anticipation and the knowledge that there is nothing you can do to prevent yourself from jumping out of your skin is enough to make you want to hit fast-forward (or just skip ahead if you’re too cool to still own a VCR). The reason you can do nothing to avoid the jolt is because millions of years of evolution have shaped your brain to respond this way. It is a reflex that saved the lives of a good portion of your ancestors over the past 4 billion or so years, as they have been forced to flee from lions, bears, and slightly larger bacteria.

But it turns out that fear isn’t only good for individuals; it can benefit entire ecosystems. Recent research into the interactions between large predators and their prey has revealed that the knowledge that something may be lurking in the bushes, waiting to pounce on you, can change the way you behave just enough to have far reaching consequences. We owe this knowledge to a population of lazy, gluttonous, raccoons who live in British Columbia’s Gulf Islands.

The Gulf Islands are something of a northern paradise. They lie in the patch of sea between Vancouver Island and the North American Mainland. Paddle a canoe along the seemingly infinite coastlines of these islands and you’re likely to see everything from bald eagles, to harbor seals, to killer whales, to sea otters. A few things you likely won’t see, however, are bears, wolves, and cougars. That isn’t to say that these animals don’t belong there; they have just been chased away by decades of humans who value a good view and the safety of their pets over robust food chains.

As a result of the lack of land-based predators, the Gulf Islands are also home to raccoons… a lot of raccoons. Some people would say too many raccoons. The thing about raccoons is that they are smart. They quickly catch on when they have nothing to fear and the consequence is that they will spend literally all day scouring the island’s beaches for clams, crabs, and whatever else they can get their grubby little hands on. This is what science calls a trophic cascade. Remove one species and watch how it all goes south.

University of Victoria PhD candidate Justin Suraci noticed the effect this was having on the ecosystems of those beaches and decided to try an experiment. Suraci rigged up a series of speakers along beaches with particularly bad raccoon problems and began blasting the scavengers with sounds of dogs barking. The results were a 66% reduction in the time the raccoons spent foraging. Suraci also tried playing the sounds of sea lions through the speakers and found that the raccoons just ignored them. Clearly it was fear of a specific predator driving the leaner diet plan. The reduction in foraging time observed on the beaches of B.C. is more than enough for ecosystems within which to stage a recover.

But this isn’t the first known evidence of a trophic cascade caused by removing top predators from a region. Yellowstone and Zion National Parks in the United States have reported that rebuilding populations of wolves and cougars within park boundaries would actually reduce soil erosion and alter the course of their rivers.

In Yellowstone, the extinction of local wolves during the 20^th century resulted in an explosion in elk numbers. Those elk graze on the vegetation along the park’s riverbanks and eventually eat all of it away. Plants along a river don’t just look nice, though; their roots actually hold the soil in place against the never ending flow of the river. With less vegetation, the rivers eroded their banks faster and generally started flowing more quickly, altering the environment for the fish and amphibians that depend on them. Since wolves were reintroduced, park officials have noted that the pattern has begun to reverse itself. In Zion, the lack of cougars is presently having the same effect on deer populations and local rivers, but cougars are slower to rebound than wolves.

In the end, it seems that if we want to enjoy the beauty of nature, we can’t pick and choose the animals we want to have around. Especially in the case of predators, removing a single species can have dramatic consequences to both, the food chain and the environment itself. The island-living raccoons in B.C. will soon wise-up to the speaker situation and resume their foraging unless their natural predators are reintroduced. God help us if they figure out how to make cups out of coconuts.

Whale Fall – More than just a hilarious existential crisis

Whale fall. It may sound like the rejected title of a James Bond movie or a Douglas Adams reference, but it is actually a surprisingly important and relatively little known concept in the study of the world’s oceans. It all begins with one of the saddest moments in the story of any whale family. Grandpa whale, let’s call him Moby, after a long a fulfilling life of eating ship captains’ legs, dies. 

As sad as this is for the rest of the whale family, odds are that if Old Moby died from natural causes he lived a pretty long life. Research beginning in the 1990’s revealed that a significant portion of the population of many whale species is over 100 years old. Questions started being asked when whale carcasses were pulled from the ocean containing stone harpoon heads, which fell out of fashion around 1860. Tissue samples from a group of Bowhead whales subsequently revealed that several were in their mid-100’s and one male was pushing 200. The point is whales can live a long time.

When a whale dies without human intervention its body either washes up on shore, occasionally with hilarious consequences, or it sinks to the bottom of the ocean. The latter is much more common and the result is something pretty remarkable.

When a whale fall, as these things are known, touches down the animals that live on the sea floor throw a party. The deep ocean is a surprisingly poor environment in terms of available food and energy with animals living mostly on small particles of so-called “marine snow” that drift down from above or by eating each other. A whale carcass, as you can imagine, is a welcome break from this kind of life.

The first phase of a whale fall food chain involves getting all that delicious, rancid flesh off the bones. That job is taken care of by animals like ratfish, sharks, crabs, and hagfish. The work goes surprisingly quickly. These scavengers can liberate up to 60 kg (132 lbs) of meat in a day. After a few short months (whales are big animals) only a skeleton remains. At first glance it would seem like the show is over, but in reality things are just heating up.

As the crabs and sharks pack up and move on to greener pastures, worms move in. Lots of worms. Polychaete worms, to be precise. Up to 45,000 worms per square meter blanket the sea floor about one year after the whale buffet opens its doors. They, along with a few other species of invertebrates, feast on the organic material in the whale bones. Although this stage of whale decay brings huge numbers of animals, they represent only a few species. The real fun begins when the microbes arrive on the scene.

Somewhere between one and two years into the show, most of the low hanging fruit (to use a more pleasant sounding metaphor) has been harvested. At this point sulphur-reducing bacteria arrive to feed on the fats and oils left in the skeleton. As they do this they release sulphur into the surrounding water, which attracts sulphophilic (sulphur-loving) bacteria. These bacteria, remarkable, form the basis for a very unique food web.

Most food webs on Earth begin with photosynthesis as plants turn sunlight into food. The web around this stage of a whale fall by comparison is chemosynthetic, meaning that it’s basis is chemical reactions by bacteria. Larger and larger animals feed on the bacteria and on the creatures that feed on the bacteria until eventually you have a booming community that includes up to 190 different species of visible animals. The only other place where this type of system exists is around deep sea vents where the energy comes from within the Earth itself.

These Stage Three whale fall communities can last a surprisingly long time. We're talking decades. Research has shown that some whale falls can sustain an ecosystem for over 50 years! And these are not rare systems. Given the number of whales alive today and the length of time that these communities last, scientists estimate that there may be a whale fall every 5 to 16 km (3 to 10 miles) along the sea floor, meaning that when the nutrients finally do run dry, the creatures that depended on them don’t have far to travel until they find their next home.

Whale falls are islands of biodiversity in one of Earth’s least bountiful places. Yet another reason why humans should do our part not only to protect whales, but to protect the fish and oceans that they depend on.