Daily 2021

Intertidal sea life

Sea lettuce, kelp, sea stars, urchin (left middle) at low tide, Bischof Islands, Haida Gwaii, BC., part of an unbalanced ecosystem.
Sea otters are a keystone species in this Pacific Northwest ecosystem. When they were hunted to near extinction in the 1800s it started to alter the ecosystem in a trophic cascade. Removal of the sea otters (predator) allowed urchins (herbivore) to expand and eat all the kelp (plant) and create urchin barrens, Species dependant on the kelp forests (fish fry, etc.) lost their habit. Kelp forests appear to be still flourishing in the Aleutian Islands where healthy populations of sea otters remain.
Adding to the problem is appearance of the sea star wasting disease in 2013 that caused a massive die-off of sea stars, another urchin predator. The result is the creation of massive urchin barrens where little else lives.
Another factor is the crash of the abalone population, which eat kelp. Abalone are now an endangered species, culturally and nutritionally important to the Haida people. Sea otters and sea stars are both predators on abalone and the reintroduction of sea otters to restore balance to the ecosystem is opposed by those who depend on the abalone for income.
A further complication is the urchin fishery. Urchins can survive for years of starvation when they've eaten their food source (kelp), but their edible roe shrinks, destroying their food value.
So complicated, but an ecosystem out of whack, further stressed by climate change as the coastal waters warm.

intertidal specieslow tideecosystemsea starssea lettucekelpurchinbarnaclesBischof IslandsJuan Perez SoundHaida GwaiiBritish Columbia