Can Otters Help with invasive Green Crabs?

Invasive green crabs threaten US West Coast ecosystems. A suggested solution: Otters. Why?

An Ecological Perspective of Sea Otters and Green Crabs:

The interplay between sea otters and green crabs highlights the complexity of coastal ecosystems. Sea otters (Enhydra lutris) are a keystone species in marine environments, primarily due to their role in controlling sea urchin populations. By preying on these herbivorous invertebrates, otters help maintain kelp forest health, which is crucial for various marine organisms.

Green crabs (Carcinus maenas), on the other hand, are an invasive species originally from Europe. Their introduction to North American waters has had significant ecological consequences. These crabs are opportunistic feeders that can outcompete native species for resources, leading to declines in local biodiversity. Notably, they consume juvenile shellfish and other invertebrates, which can disrupt the structure of marine habitats.

The interaction between sea otters and green crabs presents a unique case study in ecological management. A new study, published in the Biological Invasions journal, found that there was a direct relationship between the two species: if an area had a healthy population of sea otters, it would also have a low green crab population.

As sea otters, actually listed as threatened under the Engdangered Species Act, may expand their range, particularly along the West Coast of the United States, their predation on green crabs could help mitigate the impacts of these invasive crustaceans. A dynamic that illustrates the potential benefits of restoring ecosystems with predators where they have been historically diminished. And a dynamic that shows that Nature always has naturally balanced systems.

However, the outcomes of this particular interaction may vary based on local environmental conditions and the specific ecological roles of other species present. For instance, in regions where green crab populations are particularly robust, the presence of sea otters may not be sufficient to keep their numbers in check. Additionally, the success of sea otters in controlling green crab populations may also depend on prey availability and habitat characteristics.

So, the relationship between sea otters and green crabs offers critical insights into ecosystem dynamics. As coastal management strategies evolve, understanding these interactions will be vital for promoting biodiversity and maintaining healthy marine habitats. Continued research will be essential for devising effective conservation practices that incorporate the roles of both native and invasive species in coastal ecosystems.

What this relationship dynamics shows in any case though is that natural ecosystems — when left alone and not artificially managed by humans — are in itself balanced. A key to healthy ecosystems will be the stopping of interfering more into natural systems and let systems play out by Nature.