This illustration from the Seattle Times (link to article) provides a fascinating window into what Seattle’s marine ecosystem might have looked like prior to urbanization. It’s a map of the Seattle area circa 1851, the year that the first white settlers arrived in the area.
There are some amazing distinctions here between the geography of the area at that time, and that of Seattle as we see it today. The entire area that was once a mud flat at the mouth of the Duwamish River is now filled in and inhabited. Harbor Island, a massive man-made structure where large cargo ships now dock and unload, did not yet exist. Without dredging, the southern parts of Elliott Bay were shallower than they are today. A cove exists on the north side of the bay where cruise ships now dock.
Here’s the same illustration next to a satellite map of modern day Seattle (click on it to make it bigger):
With so much more soft sediment and so much less rocky habitat, I find myself wondering whether the rocky habitat species that are so common today – octopus, lingcod, rockfish – were barely present prior to urbanization. The area may have instead been dominated by seagrass beds and tidal mud flats, which support a very different biological community. With no long-term data sets spanning the length of the urbanization process, it may be hard to really know how the ecosystem has changed and what it looked like before the city of Seattle existed. It’s fun to think about though!