Jane Watson studied sea otters for decades, but in the 1990s a British Columbia ecologist noticed they had a destructive habit. While conservationists were working diligently to restore damaged seagrass meadows elsewhere in the world’s oceans, it seemed ironic that the seagrass habitat of North Vancouver Island, which is much larger than others in the world. Healthy, furry floaters will swoop in and dig for clams, destroying aquatic vegetation.
As she and others examined the sandy bottoms pockmarked with clam-digging pits, Dr. Watson inadvertently noted that in places with long-established beavers, grasses, also known as eelgrass, seem to flower more often.
He wondered: Were these disruptive beavers affecting plant reproduction? She sat on the idea for decades, but her curiosity later inspired one of her graduate students at the University of Vancouver Island. Years later, that hunch has been proven correct A paper published on Thursday in Science and led by that former student, Erin Foster, who is now a research associate at the Hakai Institute.
Research by Dr. Foster and colleagues suggests that sea otters are similar to eelgrass elephants. Their disturbances, as they dig for clams and remove eelgrass roots, stimulate sexual reproduction among vegetation. That sexual activity, in contrast to reproduction through natural cloning, increases eelgrass genetic diversity and improves the resilience of the ecosystems in which both otters and eelgrasses live.
The findings highlight the importance of restoring missing predators to marine ecosystems, such as sea otters, whose feeding has genetic implications throughout the environment.
Mary O’Connor, a seagrass ecologist at the University of British Columbia’s Center for Biodiversity Research, who was not involved in the study, praised the research, saying that while the genetic effects of dominant predators on other parts of ecosystems have been identified in ecological theory Understandably, “It’s really hard to see, and they’ve made it clear.”
There are two ways of breeding eelgrass, Dr. Foster says. It can reproduce asexually, cloning from roots. Or eelgrass may reproduce sexually, producing flowers that become pollinated and produce seeds. Sexual reproduction, producing unique combinations in different plants, is like playing the genetic lottery. In contrast, cloning makes each offspring genetically identical.
So during his doctoral studies at the University of Victoria, Dr. Foster designed a sophisticated test to see if sea otters were affecting eelgrass reproduction. In collaboration with Dr. Watson and 11 other ecologists, evolutionary biologists and geneticists, Dr. Foster looked for eelgrass genetic signatures, taking plant tissue samples from three types of sites in the Great Bear Rainforest and along the coast of West Vancouver Island.
In some sites, sea otters were absent for more than a century, a long-term effect of the European fur trade. On others, the reintroduced otters had existed for decades. And in a third subset of the survey sites, otters had been present for less than 10 years. Collecting hard-earned eelgrass shoots for DNA analysis, Dr. Foster predicted that eelgrass meadows with the presence of long beavers should have high levels of genetic diversity.
It also tested the effects of latitude, depth, grassland size and temperature. But she found that the most influential factor for eelgrass genetic diversity was sea otters’ length. Digging sea otters increased the chances for seedlings to germinate, increasing eelgrass genetic diversity by as much as 30 percent.
The team notes that beavers are not the only driving force behind genetic diversity. In the past, eelgrass flowering may have been fueled by the now extinct or rare megafauna, or by indigenous traditional harvesting of eelgrass. rhizomes and seeds, a practice that declined with European colonization.
seagrass meadows provide Rich food and protective habitat for marine life around the world. Seagrass-supporting otters are unusually pristine in these remote coasts of British Columbia, but elsewhere, face many threats from agricultural runoff, boating and coastal development. By better understanding the factors that may make this life-supporting undersea carpet more genetically healthy, said study co-author Chris Darimont at the Hakai Institute, this sea otter research shows “another way that a The hunter can hedge our bets against an uncertain future.”