Shell Removal Is Destroying Habitats Globally: Seashell Collectors Aren't As Harmless As You'd Think
They may seem harmless, the kindly retirees strolling beaches for beautiful seashells to give to their grandchildren. But these shell collectors may actually be an ecological menace, stealing vital wildlife habitats by the ton, a new study concludes.
The paper, published in the journal PLOS ONE on Wednesday, looked at the removal of seashells on a Spanish beach during several months, three decades apart. As tourism increased at Llarga Beach, southwest of Barcelona, the number of shells decreased, particularly during the summer months. The authors, from the University of Florida and the University of Barcelona, called it a case study with potentially global implications for animals that depend on an abundance of beach shells to survive.
Like Us on Facebook
"Molluscan shells are of prime importance to hermit crabs, and although sand beaches are not good places for such crabs, dead snail shells on mud-flats and rocky shores do form a primary resource for abundant hermit crabs," said Dr. Geerat Vermeij, a renowned mollusk shell expert at the University of California, Davis, in a news release announcing the research. He was not involved with the study. "More subtly, many small organisms settle on dead shells, and so removing such shells will eliminate habitats for these colonists."
The true scope of the problem is difficult to quantify because research on the topic is scarce. Though many have written about the live shell-dwellers, or molluscs, academia has seldom delved into the scale of dead-shell harvesting by well-meaning collectors, said co-author Michal Kowalewski, of the Florida Museum of Natural History at the University of Florida. "It's too early to tell whether this depletion is substantial enough to trigger major environmental changes," he said, but cautioned that "we should not ignore this issue" in light of their results.
By surveying Llarga Beach multiple times from 1978-1981 and again from 2008-2010, the authors found that the number of seashells dropped by 60 percent over the course of 30 years. During that same time, tourism in Platja Llarga, Spain, tripled. They couldn't find any other explanation: They observed no urban development, no new fisheries, and no significant changes to the natural environment. Moreover, the shells seemed to disappear in greater numbers at the height of the annual tourist season.
Shell depletion by more than half may seem bad, but there's reason to believe it's even worse elsewhere. The Florida Museum put it bluntly: Llarga Beach isn't all that great. "Although a popular destination, the beach is not a major tourist hot spot, and the shells found there are not beautiful, diverse, or valuable to collectors," they said. Chances are, major shell beaches such as Shell Beach in Western Australia or Sanibel Island in Florida are taking even bigger hits.
In some places, like the Bahamas, the collection of dead seashells is restricted. In Florida, it's illegal to harvest certain live mulluscs without a license. According to seashell-collector.com, several islands have restrictions, and France (for some reason) has banned mullusc collection using a flashlight.
© 2012 iScience Times All rights reserved. Do not reproduce without permission.