A study relates seashell loss to tourism

In the 1980s, the scientific team from UB started to collect shell samples on Llarga Beach in Salou (Catalonia, Spain).
In the 1980s, the scientific team from UB started to collect shell samples on Llarga Beach in Salou (Catalonia, Spain).
Research
(15/01/2014)

A study published on the journal PLOS ONE demonstrates that increased tourism on the Mediterranean coast correlates with a 70 per cent decrease in mollusc shells during the tourist season in July and August and a 60 per cent decrease in other months. The study is signed by experts Jordi Martinell and Rosa Domènech, from the Department of Stratigraphy, Palaeontology and Marine Geosciences and the Biodiversity Research Institute of the University of Barcelona (IRBio), and Michal Kowalewski, from the University of Florida (USA).

In the 1980s, the scientific team from UB started to collect shell samples on Llarga Beach in Salou (Catalonia, Spain).
In the 1980s, the scientific team from UB started to collect shell samples on Llarga Beach in Salou (Catalonia, Spain).
Research
15/01/2014

A study published on the journal PLOS ONE demonstrates that increased tourism on the Mediterranean coast correlates with a 70 per cent decrease in mollusc shells during the tourist season in July and August and a 60 per cent decrease in other months. The study is signed by experts Jordi Martinell and Rosa Domènech, from the Department of Stratigraphy, Palaeontology and Marine Geosciences and the Biodiversity Research Institute of the University of Barcelona (IRBio), and Michal Kowalewski, from the University of Florida (USA).

Global tourism has increased fourfold over the last 30 years and harmed many natural habitats worldwide. In the 1980s, the scientific team from UB started to collect shell samples on Llarga Beach in Salou (Catalonia, Spain), a town where the number of tourists visiting the beach increased threefold since 1970.

 
Collecting thousands of shells on Llarga Beach

“First, the idea was to study aspects related to predation in the species Chamelea gallina,but then the research was reoriented towards the relationship between tourism impact and shell accumulation rates on the beach and, consequently, towards coastal benthic ecosystems and sedimentation”, explains Professor Jordi Martinell, head of the Research Group on Paleobiology of the Mediterranean Neogene of UB. “We are palaeontologists —stresses Martinell— and we are interested in studying current bio-sedimentary and ecological processes in order to interpret fossil records. We still have so much work to be done”.

From 1978 to 1981, UB experts identified and classified different species in order to select the most suitable ones to conduct the study. Information about taxonomy, ecology, etc. was obtained from tens of thousands shells —more than 50,000 valves of the species Chamelea gallina were collected. From 2008 to 2010, the same shoreline transects, where new hotel complexes were built, were resurveyed. Environmental (meteorology, oceanography, etc.) and economic (tourism, etc.) data were analysed too.

Professor Rosa Domènech explains that “Llarga Beach had biological and physical characteristics that were scientifically interesting: it was protected between 1978 and 1981, it is close to Barcelona, it is 600-metre long, and it contains shell accumulations throughout all the year”. Moreover —emphasizes the researcher—, we had the samples took 30 years ago; to have previous data obtained by the same researchers following the same method it is not common in scientific research”.

 
Tourism is not responsible for all changes

Shell loss may cause significant damage to the environment; it produces some alterations on beach stabilization, reduces the production of carbonate sediments, etc. “Humans may play a significant role in altering habitats through activities that many would perceive as mostly harmless, such as beachcombing and seashell collecting”, points out Michal Kowalewski. 

Authors stress that not all changes on Llarga Beach ecosystems are due to tourism. The initial hypothesis of the study was to relate the reduction of the number of shells on the beach to the increase of the number of tourist arrivals and the study has proved the correlation. However, this does not mean that it is the only factor or direct cause. “The correlation could be also explained by factors such as an increase in water turbulence, organic pollution, or dairy maintenance and cleaning services, among other causes”, highlight UB experts.

 
What will it happen on other worldwide beaches?

If a correlation between tourism impact and accelerated shell loss has been observed on Llarga Beach, the phenomenon may be more worrying in other beaches that are popular for their malacological diversity and are frequently visited by collectors. Some countries —for example, the Bahamas— limit the quantity of shells tourists can remove from shorelines. However, there is a lack of studies focused on the real impact of human activities on coastal habitats and ecosystems.

“The Mediterranean coast —state Martinell and Domènech— is not popular among collectors for containing beautiful, diverse or valuable shells, unlike the coast of Florida, Philippines or Indonesia, where significant removal activity of malacological pieces is observed”. “Even the impact exits in Spain, it is not so high”, they conclude.

UB experts affirm that “it is necessary to develop further studies, particularly on those areas popular for shells value”. “Nevertheless —emphasize authors—, to perform reliable analyses we need to have data collected some years ago and to design new working methods. In the case of Llarga Beach, we had the luxury of having data collected 30 years ago, when tourist arrivals were between 3 and 4 times lower than nowadays”.