Who Doesn’t Love a Good Octopus Story?

(c) Azcheal via Flickr Commons

Terrestrial mesopredators in urban areas (think raccoons, foxes, etc.) have been well-studied over the years, but less so in marine systems. A team of researchers from various institutions in Washington state sought to reduce this gap in our knowledge by studying the giant Pacific octopus (Enteroctopus dofleini) in Puget Sound.

In general, urban ecology research has focused more on terrestrial systems and less on marine, so it’s great to see good research out there trying to remedy this. If you’re interested in urban ecology, have access to a coast, and want a good research project, there are almost endless possibilities in marine systems.

The authors used research questions in line with much of what we’ve found with terrestrial mesopredators in urban areas: were they distributed differently in urban vs. rural systems; was abundance related to the amount of manmade debris; and did diet change in urban areas. The researchers found that octopus potentially used urbanized features and made use of urban resources in different ways than terrestrial mesopredators do.

Part of this is likely due to the fact that an octopus is quite different than a raccoon, but part of it also has to do with the added dimension that marine life lives in. Urbanization, as it turns out, appears to influence the depth at which these octopus hang out; in Puget Sound, they stay at deeper depths than in nearby rural areas. It’s unclear why this is true. Maybe it’s because there’s a concentration of predators such as seals and sea lions in urban areas, and so octopus are driven to greater depths to avoid them. Or, maybe it’s because octopus are less able to deal with shallow water conditions in urban areas (either because of the influence of the cities themselves, or because they’re located at river heads where salinity and temperature might be different) so they stay at greater depths to avoid these problems.

Octopus abundance was greater where there was more manmade debris on the floor of the Sound. It might be that the greater concentration of such debris is what makes it possible for octopus to live in urban areas, as cities often grow near the mouths of rivers or in estuaries where the substrate is soft and so lacks protection. The authors acknowledge, however, that some of their findings might be influenced by their methodology because of diver search patterns, so more research around this question is likely necessary.

However, unlike most terrestrial mesopredators, octopus diet did not seem to change in urban vs. rural areas. This is a big area of research in the terrestrial community (how does the diet of a coyote change from rural to urban settings, for example), so it’s interesting that in this case diet did not appear to be influenced by urbanization.

Much is left to be discovered about marine mesopredators in urban systems, but this study goes a long way towards both answering and delineating those questions! Hopefully we’ll see more research like this in the future.

Here, Eliza C., Olsen, Amy Y., Feist, Blake E., and Sebens, Kenneth P. 2018. Urbanization-related distribution patterns and habitat-use by the marine mesopredator, giant Pacific octopus (Enteroctopus dofleini). Urban Ecosystems: https://doi.org/10.1007/s11252-018-0742-1