Interesting yes - rockfish. Thanks for posting.
Bit of erroneous semantics by the authors - port development doesn't actually change the tides - the moon and the sun do. Port development can change the heights of the sediments in the estuary which alters what zones are where in the estuary - and how far up the estuary the tide influences.
Generally (w/o subsidence) - infrastructure like wharves and causeways slows the water down and causes sediments to drop out earlier in the estuary and raises the heights of the sediments on the river/estuary bottom. That area can include the shipping channels; while shipping often re-suspends sediments and often causes wakes that erode the banks. Changes in water flow induced by infrastructure like wharves, shore protection and sewerage pipes alters riverine & tidal flows that also causes erosional and depositional areas - as well as the dredging - which they did mention. The sea levels are also slowly rising - infiltrating low-lying areas and increasing erosion in areas.
Then there is subsidence in many port areas built on deltas where both groundwater removal and flow reductions due to river water removal causes sediments to compact in those delta areas. They did not mention this.
The authors similarly missed the opportunity to point-out that estuaries change naturally over geologic time scales from the influences of ice ages, geologic lift & isostatic rebound, and weathering. The Appalachian mountain chain on the East Coast has had ~480 million years of weathering & ice ages which has produced bar mouth bays and flooded estuaries as those sediments get deposited out into the estuary.
In contrast, the Rocky Mountains had only had ~300 million years of weathering and the rocks closest to the West Coast have had even much less than that ~80–55 million years of weathering. These estuaries an in their infancy in comparison to East Coast estuaries. Changes are inevitable and predictable - possibly with accelerated human-induced changes in localized areas - but it all needs to be put in context, compared and contrasted.
The legacy of the ice ages alone is particularly interesting wrt fish assemblages. At one time the Southern extension of the Cordilleran Ice Sheet (
https://en.wikipedia.org/wiki/Cordilleran_ice_sheet) in what is now Alaska, Western Canada and Northern Oregon cut-off the Skeena and Fraser and dumped them into the Columbia. And then the ice sheet retreated and the rivers resumed their original discharge paths. That's how the Skeena ended-up with salinity intolerant river whitefish in the freshwater while the other coastal systems on BCs coast do not - as an example (they didn't come through the salt front door). But I diverge.. back to the topic of estuaries...
They didn't really seem to get into any of this level of detail. None of these facts I relayed are particularly novel or unknown. I find it therefore misleading that they instead state: "
Rather, it is people that are changing the tides."
