Attempts to maintain the “natural beauty” of Southern California beaches are actually having a massive negative impact on the beach ecosystem overall, a new study warns.
To most people, a beach is a beach. You could likely take an image of almost any urban beach in Southern California—the flat, mostly featureless expanse of sand against blue-green water and blue skies—swap it with one of nearly any other urban beach in the area, and chances are that only a trained eye would notice the difference.
Some of these differences lie just beneath the surface, however, and are quite important ecologically. Dig just a few inches into the sand and you’ll find it teeming with life such as sand crabs, clams, and beach hoppers.
But for about a third of the sandy beaches extending from Santa Barbara to San Diego, only a small subset of these highly specialized beach animals remain, and in reduced numbers at that.
Cities up and down the coast have flattened dunes, destroyed native vegetation, and groomed the sand with heavy equipment such that what many of us have come to call “natural beauty” is in fact about as natural as a sand parking lot.
All of this, scientists write in a new paper in Ecological Indicators, has massive impacts on the larger beach ecosystem. Further, it could already have had negative effects in terms of erosion, sea level rise, and the health of the surrounding ocean and coastal ecosystems.
Too much grooming
“After studying mainland beaches in Los Angeles and San Diego, one of the big a-ha moments for me occurred when I went out to the Channel Islands to study sandy beaches that have never had vehicles driving on them and have never been subjected to grooming, filling, or bulldozers,” says coauthor Jenny Dugan, a coastal marine ecologist at the University of California, Santa Barbara.
On those beaches, she notes, coastal vegetation comes right down to the winter high-tide mark, sand collects in dunes of all sizes and shapes, and kelp washes onshore and accumulates in piles, providing food for an amazing variety and abundance of invertebrates, which, in turn, are food for shorebirds and fish.
Now, we’ve disrupted this well-tuned ecosystem on urban beaches, she says. Workers often use heavy machinery to rake trash and debris out of the sand—and bring large quantities of sand from elsewhere to replenish sand that storm and wave action washes away.
Workers groom some beaches daily, often twice. The frequency of disturbance to many beaches by these widespread activities is greater than any known farming or land management practice.
“We observed strong negative responses to these intense widespread practices on urban beaches in the biodiversity, structure, and function across all the intertidal zones of beach ecosystems,” says lead author Nicholas Schooler, a postdoctoral researcher at UC Santa Barbara’s Marine Science Institute (MSI).
Some of these results came as no surprise to the researchers. In previous studies, they found disturbance from beach grooming caused strong negative impacts to upper intertidal biodiversity on Southern California beaches and in one study those impacts persisted for more than three decades.
The ‘wrong sand’
The current study took a much wider and deeper look at the diversity of beach ecosystems these management practices affect, revealing the scale of impacts across the entire intertidal zone as well as the region.
“We explored how disturbance from these management practices affected ecological communities on different spatial scales,” Schooler s