For example, we weren’t long into the trip before we started seeing the kelp beds – impressively large seaweeds, predominantly two species. The kelp beds are key to the ocean ecosystem here. As I titled my first lecture, Kelp Forests: disgusting seaweeds (or providers of key ecosystem services), I compared photographs taken by divers in the B.C. kelp forests to images taken of the temperate rain forests. I focused on the similarities between the two ecosystems, not least of which is supporting high diversity and lots of photosynthesis, providing food and habitat for many other organisms. Just like the rain forests, which are important components of carbon sequestration, the seaweeds also take up enormous quantities of carbon dioxide during photosynthesis. Once the seaweeds die, a large portion of the biomass drifts into deep water, buried in ocean sediments, along with that sequestered carbon. Yet another example of an ecosystem service provided by nature.

If you want to demonstrate the importance of an organism to the overall food web, the most direct evidence is often by removing it (either directly or indirectly). Returning to my theme of connections in ecosystems, not too long ago these large kelp beds were severely reduced; their demise was clearly linked to the top-down effects of the hunting to the near extinction of a key species, higher up the food web. This brings me to one of the main highlights of the trip – the sea otters. The heaviest member of the weasel family but amongst the smallest of marine mammals, the sea otter’s main form of insulation is its exceptionally thick coat – the densest in the animal kingdom. While this fur was a major asset to its survival in the cold waters of the North Pacific, it also led to its near total demise. Indigenous knowledge and archeological work have shown that early Indigenous peoples hunted the sea otter, but the ecosystem was left in balance. However, beginning in the mid-1700s, Russians began exploring the areas of the North Pacific and realized the value of sea otter furs. They were soon joined by other hunters, fetching high prices for the much sought-after furs.

In 1911, when the world population of sea otters was estimated at only 1000 to 2000 animals, an international ban on hunting was imposed. Slowly the sea otter populations rebounded, but the near extinction of this species showed how this “keystone species” (i.e. an organism that helps define an entire ecosystem) can completely alter a marine ecosystem. The reasons are straightforward: The favourite food of the sea otter is the sea urchin, and the favourite food of the sea urchin is kelp. Once the sea otters were gone, the sea urchin population exploded and resulted in the demise of the kelp beds.

With the disappearance of the kelp forests, many other organisms were impacted. Fortunately, these otters have made an important comeback. We all loved watching them from the ship, floating on their backs, sometimes with a pup on top of the female’s belly, and then diving deep to retrieve sea urchins and other food sources.

The kelp beds, however, also have an important connection to the peopling of the Americas. When I was in university, we were taught that the first Indigenous peoples came to North and then South America during the last glacial period via the so-called “ice-free corridor” along the eastern front of the Rocky Mountains of Canada. While this relatively narrow ice-free area between the two major ice fields was used as a migration route by early peoples, we now know that the so-called “kelp highway” was also an important and early route that brought people across the land bridge between Asia and Alaska and then down the Pacific coast. As we saw on our shore landings, the kelp beds supported an impressive array of shellfish and other animals – a readily available source of food, every day of the year, for these early inhabitants of the Americas.

As we passed the seabird colony of mainly puffins on Solander Island, we saw another classic example of ecosystem connections – this time between sea and land. Seabirds forage for food in the ocean but then typically nest on land and so are sometimes referred to as “biovectors” – organisms that transport nutrients from one ecosystem to another. From a distance, one can easily see that Solander Island stood out from the other islands we passed by its lush green colour.

The thousands of birds that nest on the island are constantly fertilizing this terrestrial ecosystem with marine-derived nutrients. By that I mean the birds feed on ocean fish and other marine animals and then fly back to land and deposit these nutrients in the terrestrial ecosystem in the form of feces, feathers, eggs, and other refuse. This fertilizes the land which affects all aspects of the terrestrial ecosystem (e.g. the type and amount of vegetation, etc.). Because of this, we sometimes refer to seabirds such as these as “ecosystem engineers” – organisms that are markedly changing their environment. Seabird populations are declining globally, mainly linked to human interferences. If the seabirds go, then so do the nutrients that they supply, and the land ecosystem will also change dramatically.

Once back on land, another highlight of the trip was walking through the temperate rain forest, as centuries-old trees hovered above us. David Suzuki referred to some of these ecosystems as “salmon forests”, for much of the same reasons I discussed above with seabirds, as Pacific salmon are also biovectors, transporting marine-derived nutrients to terrestrial ecosystems. This is linked to the complex life cycle of Pacific salmon, which have both a freshwater and a marine phase. Much of the west coast of B.C. (including Vancouver Island) once supported large populations of salmon – fish that start their lives in rivers and lakes, but then, after a few years in this freshwater environment, they begin their arduous journeys to the Pacific Ocean, where they feed on other fish and invertebrates, and put on more than 95 per cent of their biomass.