Seaweed is like the second lung of the planet, right after the Amazon rainforest. Where there are sea otters, there we can find seaweed and seagrass. Sea otter populations help ecosystems capture carbon. And prevent it from converting back to carbon dioxide. How big a role do hairy mammals play in climate change?
The Sea Otter Keeps the Sea Urchins within Limits
Areas where sea otters have almost disappeared look a bit like deserts below the surface. We can see the rocky stone bottom inhabited by countless sea urchins. Their overgrowth has a disproportionate impact on the ecosystem. These places lack large seaweed – the food of herbivorous sea urchins.
Calorie sea urchins are a popular, important food for otters. In places where otters occur, the invertebrate population is low. “Without otter populations, the stability of the entire ecosystem can be lost,” said Heidi Pearson, a marine biologist at the University of Alaska Southeast.
Otters Presence Strengthens the Seagrass
Marine ecologist James Estes documented the otter’s indispensable role in the 1970s. He noticed that the Alaskan Aleutian Islands’ kelp forests had turned into an underwater desert. In contrast, in other areas, the algae prospered, along with other animals that feed and hide among the seaweed.
Sea otters use shells and snails as tools to catch crabs. By throwing them into the seagrass area, the invertebrates remove the slimy algal surface from the seagrass surface. In this way, practically hairy mammals can thrive on seagrass.
Sea otters were once widespread in the coastal waters of the North Pacific Ocean. In the 18th century, their number dropped to 2,000 individuals due to the fur trade. Although the population has grown since then, there are still not enough.
https://www.bbc.com/future/article/20200818-the-canadian-sea-otter-rescue-plan-that-worked-too-well, featured image by Gregory Smith on Flickr.
