[Coral-List] New study: Coral reef loss creates shoreline disequilibrium and increases coastal erosion

Storlazzi, Curt D cstorlazzi at usgs.gov
Wed Sep 4 22:54:26 UTC 2024


New study: Coral reef loss creates shoreline disequilibrium and increases coastal erosion.

The first part of this study was just what we expected; when we looked at short term studies globally, shores protected by coral reefs experienced less coastal erosion after storms.

But then we looked at one of the best long-term (80+ years) data sets of shoreline change in the world and found surprising results. When we looked at decades of shoreline change data across more than 240 kilometers of the Hawaiian Islands, coral reef-lined coasts were eroding faster than shorelines without reefs !?!

We hypothesize that ongoing coral reef loss is creating disequilibrium in these systems…..and probably lots of other places around the globe.

Shorelines get into a long-term, dynamic equilibrium – e.g., beaches expand over the summer and contract over winter but stay in a more or less consistent place determined by protective features (and this includes artificial defenses such as breakwaters).  But if those defenses change – e.g., you lose height in your natural breakwaters (coral reefs) – then the beaches will change and reach a new equilibrium (e.g. a ‘thinner’ beach if defenses are lowered).

In this case, the natural reef breakwaters continue to be lost, and this disequilibrium is ongoing.

It should be noted that this effect is beyond what we expect from climate change alone, which is what we assume is a primary driver of recent, accelerating coastal erosion on unprotected shores.

Please see: https://doi.org/10.1016/j.nbsj.2024.100174

Bitterwolf, S.A., Reguero, B.G., Storlazzi, C.D., and Beck, M.W., 2024. “Shifting sands: The influence of coral reefs on shoreline erosion from short-term storm protection to long-term disequilibrium” Nature-Based Solutions, 6:100174, doi: 10.1016/j.nbsj.2024.100174

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Curt D. Storlazzi, Ph.D.

U.S. Geological Survey
Pacific Coastal and Marine Science Center
2885 Mission Street
Santa Cruz, CA 95060
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