Chief Science Correspondent
When it comes to beaches, fighting erosion is almost always a losing battle. However, some efforts to earn lost ground have had moderate success - at least on the surface.
Beach nourishment (also known as "dredge and fill") is the process of pumping sand from an external source (often from offshore or upland) onto a depleted shoreline, restoring sand area. An alternative to sea walls and managed retreat, beach nourishment protects existing structures and provides beach area for tourists.
Projects have been completed on shorelines along the East Coast. Ocean City (Md.) underwent a nourishment treatment this year, from February to May 2014. Other recent projects include Rehoboth Beach (Del.), Virginia Beach (Va.), and the Outer Banks (N.C.).
"Eroding beaches, left alone, will continue to put people, as well as our cultural, historic, economic, and environmental resources, at risk for damages from hurricanes and coastal storms," the The American Shore & Beach Preservation Association stated in an online informational booklet. "Measures designed to protect our nation’s coasts and prevent or reduce damages ultimately cost less than federal disaster assistance and insurance payouts if overwhelming economic losses occur after a natural catastrophe."
However, despite the benefits of nourishment on local infrastructure and tourist economies, a recent review study suggests beach nourishment could be having a negative impact on beach-dwelling wildlife - particularly, sea turtles and small sand-dwelling invertebrates such as sand fleas and sand crabs.
Many scientists believe the invasive sand displacement associated with nourishment harms these creatures, depressing turtle nests and dislodging the sand where small creatures burrow for survival. Sea turtles possess high ecological importance for a number of reasons. They regulate the growth of sea and beach grass. They are also an interesting organism of study for evolutionary biologists, as their body design has remained relatively unchanged for millions of years.
The sea turtle population in currently undergoing severe decline, as they are endangered in Florida and threatened in all other populations. Sea turtles have undergone an estimated 48 to 64 percent decline over the past century, according to NOAA Fisheries.
Sand fleas and sand crabs are ecologically important as well, even if their benefits are less famous than those of the sea turtle. These small invertebrates are an important food source for seabirds such as pelicans and gulls. Lose the sand fleas, and we will lose the birds.
Most previous studies had demonstrated little to no effect on these populations. In a 2005 BioScience review article, Charles Peterson and Melanie Bishop assess the impact of nourishment project on the ecology of these natural populations in U.S. beaches. What they found: At least 73 percent of the studies (which were used by the government to justify the nourishment) reported fundamentally flawed results, with errors in sample design, statistical analysis, and interpretation of results.
"Substandard biological monitoring of beach nourishment persists despite the publication of reviews that provide explicit guidelines for the variables that should be monitored and the spatial and temporal scales to considered," Peterson and Bishop wrote.
At this point, we no longer have any evidence that beach nourishment is safe for beach wildlife. Had these studies not reported these harm-free results, the projects may have either been discontinued or modified.
It appears that we have been eager to employ this short-term solution to a long-term problem (as erosion continues to impact shorelines, beach nourishments must be repeated over time) without truly assessing the impact on these populations.
I grew up visiting the Outer Banks with my family each year. As a child, I would often sit by the shoreline and collect sand fleas as the waves crashed in. It only took a few shovel-fulls before I had a bucket full of the creatures. Then, in 2011, the community underwent a nourishment project. Although I no longer collect sand fleas myself, my brothers still did - at least they would have, had there been any to collect. Now, in 2014, the sand fleas still appear to have vanished almost completely from the area. And while I still see sand crabs in the evening, I do not believe I see as many as I did prior to the project.
It is time we start thinking of another solution to this problem, even if it just means modifying nourishment practices to reduce their impact. Cutting corners is not worth destroying an entire coast's worth of ecosystems.