![]() ![]() In coastal areas where sea otters regularly consume sea urchins, kelp forests have a greater chance to take hold and endure, and act as an undersea forest habitat for other marine animals.īut when there are not enough predators like sea otters to feed on sea urchins, the urchins graze over and effectively wipe out kelp forests. He would go on to realize that sea otters are a keystone predator that increases the abundance of a diverse array of sea life. This was my 'aha moment,' a profound realization that would set a path for the remainder of my life."Įstes had seen what is now known as an urchin barren, the result of a trophic cascade. "When I looked down at the seafloor, I was stunned by the vast numbers of urchins and the absence of kelp… Every place I looked was the same-large and abundant sea urchins over a seafloor of crustose coralline algae with little or no kelp… In the absence of sea otter predation, sea urchins had increased in size and number, and the larger and more abundant urchins had eaten the kelp. Image courtesy Grant Callegari/Hakai Institute.Īs he tells in Serendipity, what he saw when he put on his scuba gear and entered the waters off Shemya shocked him: A carpet of green, purple and red sea urchins turning a kelp-bed ecosystem into an urchin barren. He found that about 350 kilometres to the west of Amchitka, off a remote island called Shemya. ![]() To understand the relationship between the two, Estes needed to find an area that was devoid of otters and see what the kelp forests looked like. Rather than wondering how the kelp forests affected otters… why not explore how the otters affected the kelp forests?”Įstes’s observations revealed an “extraordinarily high” sea otter population around Amchitka, inhabiting a lush undersea world of kelp forests. “Bob listened to my account of what I had seen while diving," Estes recalled in his 2016 memoir Serendipity, "and what I thought it might mean and then abruptly suggested a simple but radically different change in perspective. But Estes didn’t understand the real meaning of what he’d seen until a meeting with veteran ecologist Bob Paine. Sea otters, in turn, are equally voracious predators of sea urchins. Sea urchins are voracious grazers of kelp. The crucial connection, he discovered, was sea urchins. ![]() Observing sea otters and kelp beds on Amchitka - both onshore and during scuba dives - led Estes to question the links between them. Despite the Cold War considerations that placed him there, his research ended up transforming our modern understanding of coastal ecology. The Atomic Energy Commission had sponsored his research there ahead of a contentious nuclear test on the island. Estes traveled to Amchitka Island in Alaska’s Aleutian archipelago to study sea otters. One of them is cute and fuzzy - the other one, less so. Researchers have also discovered that kelp forests in the northeast Pacific can be dramatically impacted by the presence of two predators. They are sensitive to temperature, ripped up by storms and affected by currents and waves. Kelp forests are influenced by a huge range of physical and biological factors. The abundance of food now known to be generated by kelp forests has influenced the rise of the kelp highway hypothesis: the idea that the first ice-age human populations to expand southward from Beringia did so by exploiting the rich marine resources of ice-free coastal regions, rather than migrating via an inland corridor between ice sheets. Image courtesy Tavish Campbell.īy creating nearshore habitats rich in fish and other sea life, kelp beds have been significant assets to human coastal communities for thousands of years. In British Columbia and much of the northeast Pacific, kelp beds are generally composed of clusters of whip-like bull kelp (Nereocystis luetkeana) seen in this photo, as well as giant kelp (Macrocystis pyrifera). The stipes and fronds of a kelp forest create a three-dimensional lattice that benefits everything from invertebrates like snails and anemones to marine mammals like seals and whales - providing food, hiding places and shelter. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |