Photos of marine life growing on seawall
Big Ideas

Living Seawalls for the Intertidal

It’s a bit old at this point, but I recently came across this article in Conservation Magazine on “How to Build a Living Seawall”.  It gives a good summary of work done by colleagues at the University of Washington and the University of Sydney on different seawall configurations that support greater intertidal biodiversity.  More updates as these findings are incorporated into the construction of a new seawall in Seattle…

Photo of Seattle from Don Armeni Boatramp
Background, Ecosystem Services, Historical Context

Urban Marine Environments as Coupled Human and Natural Systems

Over the last decade, a growing faction of scientists in the world of ecology and conservation biology has pushed the idea that most ecosystems on Earth are now comprised of coupled human and natural components.  They’ve come up with a variety of different names of these entities, but the one that I like most is “Coupled Human and Natural Systems,” or CHANS.  The idea is that although we’ve spent decades studying natural ecosystems, we have to take a step back and include humans before we can really understand how ecosystems function.

The literature describes several key qualities of coupled human and natural systems.  They are structured in a hierarchical manner and consist of complex networks of interactions.  These interactions are commonly reciprocal, with humans acting in ways that influence natural components, and natural components in turn influencing humans.  They also may involve positive or negative feedback loops that can accelerate or decelerate key processes.  Coupled human and natural systems exhibit emergent properties, which differ from the properties of individual system parts.  They exhibit nonlinearity in their dynamics, and may shift between multiple states or equilibria when certain thresholds are exceeded or system resilience is reduced.

If that sounds like Greek, don’t worry, I’m not here to drone on about models or theories.  I simply wanted to introduce the idea of CHANS.  By definition, CHANS are systems in which natural and human components interact. It’s undeniable then that urban marine ecosystems qualify.  Graphical model of human and natural interactions in urban marine ecosystemsThey are created out of long, intense interactions between humans and nature. Does the theory above then  give us insight into how urban marine ecosystems function? Do urban marine ecosystems evolve over time according to the theoretical framework for CHANS?

As I explore urban marine ecology in posts and research, I will do my best to highlight the coupled human and natural components of the system.  This may come in the form of historical information about interactions between humans and urban marine environments, explorations of the ecosystem services urban marine environments provide, and evaluations of these systems through the lens of resilience theory.  It may seem tangential at times, but the bottom line is that urban marine ecosystems are not just comprised of the marine organisms we encounter underwater.  Humans are very much a part of the ecological processes in urbanized marine habitats, and we may not be able to understand these processes or habitats until we have fully integrated ourselves into the ecological picture.

Recent Research

Could jellyfish blooms be attributed to “ocean sprawl”?

Photo of Jellyfish by Ole Kils

Image by Ole Kils

You may have heard that jellyfish are taking over the world’s oceans, proliferating at a rate that is unfounded by historical standards.  Is it possible that this has been facilitated by the urbanization of coastal ecosystems?

This is the question posed by Carlos Duarte and colleagues in a recent a paper published in Frontiers in Ecology and the Environment (link). Many jellyfish have two life stages: the pelagic, medusoid phase that probably comes to mind when you think of jellyfish, and a juvenile stage in which they are attached to the bottom as tiny polyps. Most previous studies that have tried to explain recent increases in jellyfish abundance have focused on the pelagic stage.  Tiny polyps are hard to find, and have thus not been a central focus for research.

That is until now… Duarte and colleagues searched far and wide for the tiny creatures.  Where did they eventually find them? On the underside of floating docks, buoys, riprap and other artificial structures. They suggest that the proliferation of artificial structures (which they identify as “ocean sprawl”) is precisely what has allowed jellyfish populations to explode.

Many questions remain, of course, and much more must be done to see if their theory holds water. While Duarte et al. found that jellyfish polyps of some species favor shaded habitats, has the increase in shaded habitat associated with “ocean sprawl” really been sufficient to facilitate the types of increases we’ve seen in adult jellyfish populations? Does the trend extend to species they have yet to test experimentally? And can we actually find these polyps on our local floating docks prior to jellyfish blooms? All of this remains to be seen.

Map of population change in US coastal watersheds

Why Urban Marine Ecology?

Despite all my hype about urban marine ecology, it’s a field that really doesn’t exist yet. At least not in any standardized or formal way. It’s a discipline in the making, inspired by the explosion of research in terrestrial urban ecology and a void of comparable knowledge when it comes to the marine environment in cities.

You may have seen the statistics about coastal population growth. Overall, it’s estimated that we will reach a population of 8 billion in ten years. Currently about 50% of people live in coastal areas, but by 2025, it’s expected that that percentage will increase to 75%. That an estimated 6 million people living within 100km of a coastline!

The movement of people to coastal areas is not uniform. Check out this graphic from the National Oceanic and Atmospheric Administration (NOAA) of population change in coastal watersheds (link). From this, you can see that population in more rural coastal areas is actually decreasing. People aren’t just moving to the coasts. They’re moving to coastal cities.

What will be the effect of population growth on marine ecosystems?  We have no idea.  Not only are we limited in our understanding of what these will look like in the future – we know almost nothing about the characteristics of urban marine ecosystems today.  Much work is needed to characterize the biodiversity of these systems, understand their ecological processes and identify how they differ from their natural, more rural ecological counterparts.  In many respects, these are systems of our own making. Don’t you want to know what we’ve created?  I certainly do.  There’s much work ahead!


Photo of Seattle from the water


Welcome to the Urban Marine Ecology blog!  Here, I will posted the latest in Urban Marine Ecology research, as well as reflections on general concepts and paradigms in the field, historical information I uncover relating to urban marine environments, and updates on my own research.  For more information about me or my work, please see the other pages of this site.  I look forward to any and all feedback.  Thanks for reading!