Study: Seashell Loss Due to Tourism Increase May Have Global Impact 8 January 2014

Study: Seashell loss due to tourism increase may have global impact 8 January 2014

Global tourism has increased fourfold over the last conditions, which could potentially contribute to a 30 years, resulting in human-induced seashell loss natural decrease in shell numbers, were not that may harm natural habitats worldwide, observed, he said. according to a University of Florida scientist. Shell removal at Llarga Beach was higher during Appearing in the journal PLOS ONE on the summer, and shells were more abundant during Wednesday (Jan. 8), the new study by researchers the winter when fewer tourists visited the area. from the Florida Museum of Natural History on the Although a popular destination, the beach is not a UF campus and the University of Barcelona major tourist hot spot, and the shells found there demonstrates that increased tourism on the are not beautiful, diverse or valuable to collectors. If Mediterranean coast of Spain correlated with a 70 a relationship between increased tourism and percent decrease in mollusk shells during the accelerated shell removal can be detected at a tourist season in July and August and a 60 percent place that is not famous for its shells, it is likely that decrease in other months. Scientists fear shell beaches known for their shells and frequented by removal could cause significant damage to natural collectors have had more substantial impact, ecosystems and organisms that rely on shells, said Kowalewski said. lead author Michal Kowalewski, the Thompson Chair of Invertebrate Paleontology at the Florida "Although significant research has been done on Museum. the impacts of human activity on live shellfish, including, recreational harvesting and curio "This research is best described as a case study collecting, we are still lacking rigorous studies that evaluates shell loss due to tourism and then estimating the scale of shell removal by humans," explores how this process may affect natural Kowalewski said. "Shells are remarkable in that habitats," Kowalewski said. "It's too early to tell they serve multiple functions in natural ecosystems, whether this depletion is substantial enough to from beach stabilization to building materials for trigger major environmental changes. However, bird nests." our results suggest that we should not ignore this issue." Shells also provide a home or attachment surface for diverse marine organisms, including algae, In the study, researchers conducted multiple seagrass, sponges and other micro- and macro- monthly surveys from 1978 to 1981 and from 2008 organisms. Hermit crabs use shells as their to 2010 on Llarga Beach, a small stretch of protective armor, while fish use shells to hide from shoreline on the coast of Spain. Based on area predators. These discarded exoskeletons of hotel sales data, researchers estimate the number mollusks, including clams and oysters, are also of tourists visiting the beach increased threefold important because most are made of calcium over the last 30 years, with most visits during the carbonate and in many coastal habitats they summer. Over the same time period, the number of dissolve slowly and recycle back into the ocean. shells on the beach decreased by more than 60 percent. The survey area has experienced no new The study may prompt more systematic commercial fisheries or urban development since assessments of shell removal by tourists, said the 1970s, suggesting human activity unrelated to Geerat Vermeij, a mollusk shell expert and tourism is unlikely to have contributed substantially distinguished professor of geology with the to the shell loss, Kowalewski said. Changes in University of California Davis who was not involved ecosystem structure and local environmental in the study.

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"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," Vermeij said. "More subtly, many small organisms settle on dead shells, and so removing such shells will eliminate habitats for these colonists."

Though tourism-related shell loss may one day prove harmful, Kowalewski said more rigorous quantitative case studies are needed to fully understand the impact and develop reliable beach management practices aimed at shell protection. Some countries already recognize the negative effects of shell removal, including the Bahamas, which limits the quantity of shells tourists can export without special permits.

"Humans may play a significant role in altering habitats through activities that many would perceive as mostly harmless, such as beachcombing and seashell collecting," Kowalewski said. "It is important that we continue to investigate the more subtle aspects of tourism-related activities and their impact on shoreline habitats."

More information: dx.plos.org/10.1371/journal.pone.0083615

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